Hello my pretties, the time has come for me to finally get off my lazy bum and try to update a project I began working on ages ago. Namely providing a detailed and informative guide to Kidō. So, to start off, what exactly is Kidō? Me and others who think as I do define Zanjutsu, Kidō and Hakuda as being conglomerations of all styles and disciplines of the human world. Therefore, Zanjutsu is composed of every single sword discipline ever to have existed in the our world, further refined over millenia in Soul Society. Hakuda is likewise composed of every single form of martial arts ever practised, and is gradually approaching perfection.
So by now you ought to catch my drift, Kidō encompasses every single tradition of magic ever to have existed in the human world. It's taken the values of each of these crafts and internalized them and made them into tools of war. Rituals that might've taken humans weeks to complete can be done by Shinigami with astounding ease. That's the power of spiritual energy after all. Magical traditions of our world were usually ceremonial in origin, and involved doing something specific, often at a specific time and with a specific thing.
Our forefathers would find the strangest ways of using "magic", such as a spell of spirit summoning involving the caster actually getting the keys to a house where a resident had died. Only to enter it at the stroke of midnight and dangle the keys in the middle of the attic in the hope of conjuring up the spirits of the departed. There'll be none of that in this guide though, no necromancy, no sir. Without me dawdling anymore, let's get straight down to business shall we!
How does Kidō work?[]
Obviously, to be able to go in-depth about anything you first need to understand how it works, and that's where I come in. Naturally, this is my own opinion, but me and most of my friends have taken to consider it true for the purpose of our characters and roleplays. Because when you're roleplaying with another user, it can get very complicated if you don't have a clear definition of how your characters abilities works.
We should all be familiar with the whole concept of spiritual energy, so I'll get my own explanation out there. Imagine each trace of spiritual energy to be composed of innumerable fragmented wills, like a very small trace of whomever died around that area. These minuscule spirits would not possess a mind of their own, obviously, and most of the time they'd have no bearing on their surroundings at all. But when you use Kidō, this all changes. With this form of spirit magic, the Shinigami would hone each of these fragments into a singular purpose, that being in the form of a spell.
Incantations serve the purpose of guiding these wills to accomplish the task set before them, allowing the caster to unite them much more efficiently. This does not however mean that Kidō isn't taxing on the caster though, merely because it usually employs external forces to work, on the contrary, the drain on a casters resserves are typically quite significant depending on the power of the spell, but if you're good, you can produce spells of immense power while expending a minimal amount of energy to power it. Broken down, it works like this.
Firstly, you draw upon your own energy, attracting these minor spirits to your cause. This is the initial gathering of energy and constitutes the very beginning of the spell. This is where raw power is decided - the greater your skill and power, the stronger the pull towards you will become. This is why casters like Byakuya are capable of casting simple spells and still have them boast immense potency.
Secondly, you invoke them in the form of a spell, having them rally under your command. This is where you'd typically begin the incantation, but those skilled enough might accomplish the same with merely the name of the spell, or for the greatest of masters, mere thought. This is the point where the speed is determined.
Finally, you complete the command and release your thrall over the spirits, freeing them from their bindings in the form of a glorious spell. They're now enthralled to the Kidō users will and are guided by it, taking shape into the desired spell. Once the spell is complete they dissipate back into the atmosphere as before, where they might be wielded again.
What's the point of Kidō?[]
Right. This sort of section is neccessary because I feel that there's a lot of you who simply don't see the immediate use of Kidō. After all, what Kidō can do, Zanpakutō can do better, right? Well.. this isn't the case at all, there's a myriad of reasons why Shinigami use Kidō , and not only do they use it, but it's used with high frequency, even by characters who aren't proficient at it. An obvious example would of course have to be Renji.
The reason is remarkably simple, if we look at a basic Shinigami and a basic Hollow, the latter possesses pretty much every single physical advantage over the former. In a close ranged confrontation the Hollow would probably destroy the poor Shinigami, it's natural weapons and defenses are flat out superiour. Such a creature requires much more than simple katana skills to defeat - and that is where Kidō is important. Kidō allows you to fight opponents you otherwise couldn't have faced, it allows you to create advantages where at first none existed, and it can turn difficult battles trivial, that is the power of Kidō . From the onset, it is probably the singularily most powerful piece of the Zankensoki. Both Zanjutsu and Hakuda, when practised at a basic level both pale in comparison to Kidō .
Which brings me to another point, the sheer utility of Kidō is simply tremendous. Especially focused within the Bakudo branch of the artform. Spells like Tenteikūra and Kakushitsuijaku are practically indispensable for any self-respecting officer. They both grant you tremendous uttility and allows you to be useful in situations where simple combat skills wouldn't cut it, you can be a master of physical combat as much as you want, but if you can't get to the enemy it won't matter, you'll just be yet another typical Shinigami with a Zanpakutō. Even if you're a lot better at swinging it around. I don't know about you guys and gals, but if you were a Captain looking through Lieutenant applications, would you look for someone to stand on the frontlines waving their sword around or would you rather prefer someone who claimed to be good at healing, creating barriers and assisting the frontline with powerful binding spells? I would certainly have prefered the latter, because the latter would've been more likely to ensure success for me and my troops. We've already got a character like that in canon, Nanao Ise. Who claims that she was appointed a Lieutenant solely for her skills in Kidō . In the recent arc, we've got to appreciate just how true that really is.
Lastly is power. In a world where spirtual energy determines pretty much everything, the ability to seize hold of the environment, manipulate it to your own designs and answer virtually any known threat is exceptionally useful. Kidō spells, often understimated or taken at face value based upon their numerical ranking, which designates difficulty not neccessarily power, allow you to greatly increase the options of your character. Rather than merely hitting someone hard, it allows you to make your character invisible and untrackable through wonders like Kyokko or deal with opposition instantly in the form of Hakufuku. When cast by someone skilled, Kidō can even rival or exceed the power of a Bankai. Although this is true for pretty much any of the four branches of Zankensoki, I believe it especially true for Kidō .
Blending Kidō with Character[]
This is the section where I'll start discussing some relevant applications of Kidō in regards to various "classes" of Kidō Users. Now, at this point you might arch your shapely little eyebrows and wonder what I'm on about, so I'll explain. There's practically infinite variety on how to use Kidō , there's no clear-cut way, this allows you to blend it in with your character - but as this is a Kidō guide after all, I'll work on the basis that each character is a master in their particular brand of Kidō .
The first class I'm gonna discuss here, and the most common class on this fanon is the Kidō-Fighter. The Kidō-Fighter is a character who has mastered the typical Gotei 13 form of Kidō, in other words the kind practised by canon Shinigami - these characters typically don't focus on Kidō exclusively, and it's instead employed as a way to increase their versatility or as a path to achieve something else. In battle, a Kidō-Fighter uses Kidō in a way which synergizes and accentuates his/her own preferred fighting style, they've managed to incorporate this artform into their usual rhythm of combat. I think it's important to note that Kidō-Fighters can either be characters like Byakuya, who simply happen to use Kidō with great frequency, or, to provide a closer canon representative, Aizen.
We all know Aizen, it's hard not to considering that this is a Bleach Fanon, and when you think of him, you typically think of Kyouka Suigetsu. But it should also be noted, that from the perspective of the original story, Aizen is probably one of the greatest Kidō Masters introduced. In battle, Aizen blends magic and Zanjutsu with remarkable ease, casually blocking attacks with conjured barriers even as he destroys the opposition with his overwhelming power. El Escudo, the spell he cast to block Shunsui's Zanpakutō was cast silently, with no more effort than it would take to swing his blade, briefly eliminating the greatest weakness of Kidō .
Now, there's currently a single fanon example I'd like to bring up here, and that would be Seireitou Kawahiru - who I believe embodies this concept fairly well. There's undoubtably others, but this is my most recent example. This class is something I'd reccomend to those who'd like to tap into Kidō and be efficient with it, without sacrificing much or having to spend too much time working on refining the character
The second class, and the one me and my friends typically imagine when we're talking about Kidō Masters is what I'd like to call the Battle-Mage. As the name would imply, this is a character who relies almost exclusively for Kidō for combat, they wield the elements, erect powerful barriers and destroys their enemy with a myriad of different spells, each cast in unison and with purpose. Their magic fulfills the same role that Hakuda or Zanjutsu typically does for less specialized characters. Typically, characters like this hail from the Kidō Corps, but this isn't always the case - even if most examples I can think of do. Silent Spellcasting is very common among most Battle-Mages, as it allows them to respond to an opponent as quickly and as fluidly as if they were wielding a blade. They usually protect themselves with powerful warding spells placed before combat, these wards activate when they're attacked and prevents them for being harmed, allowing them to focus entirely on their spellcasting until all their wards have been broken. Something of a running theme about those created so far is that they have attained complete mastery of a few spells, which they can cast at will and manipulate to suit their needs on the fly. These spells essentially form the bulk of their offence, with other spells smattered inbetween as neccessary. They often become as iconic to their character as Zanpakutō.
These Shinigami, while they may have Zanpakutō, are most likely not proficient at using them, because the pursuit of Kidō mastery leaves little time for Jinzen. Besides, as most of these are members or former members of the Kidō Corps, they've never had the same focus on achieving Shikai or Bankai as regular Shinigami of the Gotei 13. However, there's few things more powerful than a well-done Battle-Mage, with the ability to protect themselves at will, and with access to immense destructive power, these individuals tend to be exceptionally hard to injure, while utterly overwhelming their opposition with a barrage of mighty spells, and wielding the environment itself as a weapon. There's two examples from canon, one which is an actual Battle-Mage, in practise anyway, and another who simply happens to fight like one. The first one is rather obviously, none other than Hachigen Ushoda, the Kidō Master who defeated Barragan. The second is Byakuya Kuchiki, whose Senbonzakura Kageyoshi makes him fight in a manner which is very reminescent of how a true Battle-Mage would fight. For an example I'd advise watching this video from about 5:50 to 7:20. It should fully illustrate the matter.
When it comes to fanon examples, there's really only two that I remember. Kazuya Kuchiki, who I believe embodies this concept better than my very first character, Hiroya Ginkarei. There's also Midori Jinkou, incidentally the teacher of Kazuya. Unfortunately, she's undergoing something of a rehaul at the moment, so there's not much to get from her present state, although you could always go back through her history and look at older edits. It's almost impossible to roleplay as a Battle-Mage without being extremely detailed with all you do, it's also important to know that the true strength of a Battle-Mage does not lie in casting spells of very high level, but of stringing together multiple spells of lower rank into extravagant spell-chains. If you love writing long posts in roleplay, like I do, you should love this class. But if you don't wish to put in that kind of effort, you'd be better served with the Kidō-Fighter.
The last and final class I'll be detailing today is the Magus. This is the mage who inflicts harm upon and repedeatly sabotages their enemy through various rituals of magic, including enchantments and vile curses. If the Battle-Mage is the wizened wizard who blows you up with a fireball, then the Magus is the evil mage who turns the hero's love interest into a frog and locks them in a tower. Kidō is an expansive art, and one which does not neccessarily require the caster to be anywhere close to their target, such a spellcaster could attack their enemies from afar, casting spells and invoking greater powers to weaken their opposition without them being none the wiser. Magi are typically lacking in direct combat, being much more powerful when they're left to their own devices, researching powerful spells with which to make their enemies lives a living hell. Most spells of this magnitude are only to be found within the archives of the Kidō corps, so these characters are usually either part of, or have contacts within the corps. Such spells cannot readily be used in combat, because they usually involve long incantations who might range from ten to a hundred verses.
But with the powers at the command of a Magus, combat is rarely neccessary, often they can employ magic to charm more powerful individuals to fight their battles for them, while turning their foes allies into bitter enemies. As expected, there's really no canon examples of this, as this class is mostly non-combative. Another semi-combative version of this is the Magus who relies upon magical traps on the battlefield to defeat their target. Generally, a Magus forced into a battle will tend to rely upon spells who deter the target, such as binding spells or illusions. They're usually skilled in Shinigami Kidō and therefore often possess at least a smattering of offensive power, though this would be nowhere near to the calculated magical onslaught of a Battle-mage, or the synchronized spellcasting of a Kidō-Fighter. Their objective towards a more powerful opponent would usually be to secure their own escape.
There's at least one fanon example I can provide you. Namely my very own Shigenaga Arma. Now, as has been stated before, Shigenaga is much more of a political threat than a physical one. But when he's safe in the confines of his palace, protected by more than a hundred powerful bodyguards, he's capable of using occult rituals to secure his own wealth, dominate people to get more underlings or even change fate around his enemies, dooming them to experience misfortune. If his underlings were to defy him he would summon forth a famine to destroy their harvest. If he were ever to be confronted he would summon forth powerful servants to deal with the threat in his place, such as powerful Diabolus. He might engage in a supportive role in such battles, further decreasing his victims chance of success by using illusions and enchantments to strike at their mind, but if his summoned muscle was ever to be defeated. He'd probably just run, and I mean run, as he's unable to use Shunpo. This type of character requires quite a bit of research on your part, not merely in regards to Kidō or the bleachverse, but also with magic in general. If that's something you'd be interested in doing, go ahead, if not, do something else.
How do I use Kidō?[]
Without a section like this, this wouldn't be as much of a guide as it would be be a monologue. Well, to start off, I'd advise that you remove any preconception about the ranking system, there seems to be a prevalent misconception that only the higher-level Kidō spells are worth casting. That unless your character is capable of casting spells in the nineties then they shouldn't use Kidō in combat. Allow me to correct that notion now, for whomever has it, rank signifies two things, difficulty of casting and scope. A Shakkahō might turn out to be just as effective as a Kurohitsugi spell, all depending on the situation, and even if it isn't, it's always MUCH more efficient than one. Generally, because of this, Kidō spells often become more situational the higher ranked they are.
In the next section I'll be analyzing several noteable Kidō spells with the intent of giving you an idea when to use them, and what purpose they serve. But that's then, time to focus on now. Kidō spells accomplish many things for your character, the first and most immediately obvious is that they provide a secondary source of options to all Shinigami who can use them. This is a huge boon to have, believe you me, with Kidō your character could reach beyond their own personal power and defend or attack in ways their basic abilities would not allow. This is why I'd argue that Shinigami have a huge advantage over pretty much every other race.
I'll also go on saying that most Kidō Masters on this site are in fact Experts. Being able to cast high-level spells without incantation does not make you a master, nor does having knowledge of barriers or other more obscure forms of Kidō . Magic is broader than pretty much any other facet of the Zankensoki, and you need to embrace this if your character is to be a master. A single paragraph with the phrase "Kidō Master" slapped in front of it does not cut it. If you are to be considered a Master, there's really much more to it. I'd strongly encourage everyone who seriously wants their character to be a Master to make another section in the Powers & Abilities section specifically tailored to this.
Anyway, back to the point. While using Kidō , even with a character who is mostly not all that proficient, try to use them in combination with one another for added effect. Kyokko could be applied to pretty much any Kidō spell if your level of skill was high enough, providing a stealthy attack that is likely to catch the unwary opponent off-guard and secure you an immediate advantage. I've employed Kyokko and Saju Sabaku together multiple times in the past, and on many occassions it has allowed me to win the fight immediately, regardless of how good my adversaries other skills were.
Feel free to be creative, create your own spells and combine others. Make clever use of Kidō nets, and just look for inspiration anywhere you can find it. Now, there's a few things we need to go over. Firstly, casting several spells in quick succession is effective only if you have some reasoning behind the barrage. Merely throwing around spells willy nilly won't accomplish much more than wasting your characters energy, not all characters can, or should fight exclusively with Kidō spells. Secondly, Kidō spells are -not- techniques, a technique utilizes a characters personal strength and power, spells utilize external sources of power, hence why they're powered with an incantation. Simply adding more energy into the casting process won't necessarily increase the power of the spell, it might even cause it to fizzle if you're unable to properly reconcile your own reiryoku with the energies gathered externally. This is it's necessary to have great control over the flow of your own spiritual energy to have an aptitude at Kidō .
Thirdly, do not ever consider a Kidō spell to be limited. Kidō spells can manifest in a plethora of different ways, a Shakkahō typically manifests as a sphere of red energy, but as Izuru demonstrates it can also manifest as a blast of fire if neccessary. If you're an Expert, it's possible to make basic changes to the manifestation itself, if you're a true master you can make each spell elaborate. A favorite of mine being to turn spells into the shapes of animals who trail after their target. This is a degree of versatility which your typical techniques simply don't have. Use it for all it's worth. Now then, on to the promised Kidō -help section.
Kidō Spell Analysis[]
In this section I will briefly talk about a number of Kidō spells, their uses and strengths, a few ways you could improve them a bit, and generally just give you an incentive to use them more in combat.
- Purpose: For many Shinigami, this is the default offensive spell. It's purpose is to serve as a long-ranged form of offence, and it's also one of the primary ways an Academy Student can successfully defend themselves from Hollows, which is likely why it's taught so early. Unlike it's sibling Sōkatsui. It'll inflict more damage on a single target, who'll suffer both extensive fire damage and concussive trauma. In many ways a typical Shakkahō can be likened to a bomb, as it typically explodes upon contact. Also, it can be used for utility, by lighting a fuse or providing a source of light.
- Comments: Shakkahō is a spell that's cheap to cast and which deals a significant amount of damage, it can be used to breach defenses you don't want to deal with, keep your enemy at bay, or even being fired in quick succession. A feat which was performed by Renji, proving that it ain't that diffcult to do. Simple improvements to this spell could be increasing it's single-target damage potential, or make it into a classical fireball spell with a greater explosion upon impact.
- Purpose: As alluded upon in the Shakkahō entry, the primary allure of this spell is that it's conical, making it possible to wipe out a score of weaker enemies all at once. But there's another facet to this spell which may not be widely known. It's perfect for dealing with large Hollows. This is because against smaller targets, they'll only be affected by a piece of it's full power, a large Hollow might be struck by the entire spell, greatly increasing the damage it would take. To a point that would put a Shakkahō to shame. Another reason that it's widely known among Shinigami.
- Comments: When we compare Sōkatsui to it's sibling, we generally consider the former to be more elegant and refined. While this is true, there's another difference that's worthy to consider. The truth is that Sōkatsui is what I would refer to as a soft spell, it's formless and thus harder to defend against. While you might be able to block a Shakkahō by swinging your sword, you could not do the same to this spell, the flames would reach you regardless. Of course, in the used example, the Shakkahō would still blow up in your face, but that's another story. Furthermore, because it's a soft spell, it can be used to disrupt certain defenses and techniques, like Byakuya demonstrated against poor Renji. Sōkatsui is however not as easily modified as Shakkahō is, precisely because of it's soft nature. But an obvious improvement would be to cause it to fill the air around you like a self-centered explosion.
- Purpose: It's easy to guess at the purpose of Kyokkō, it's meant to hide the user from sight and conceal their spiritual energy, allowing them to either make a clean escape or prepare an ambush. I'd imagine that Kyokkō is an Omnitsukido favorite, no doubt in my mind about that. It's a spell that only hides the user from spiritual and visual sense however, and it doesn't disguise them from the other senses. The Omnitsukido though, and Hohō specialists in general should be able to move silently, making this an excellent spell for assassination, spying and surviving.
- Comments: On it's own, and when wielded on a basic level, Kyokkō is a very powerful spell, useful in a myriad of different situations. But when used by a master or an expert capable of changing around a bit on what it can or cannot affect, the spell turns from a very powerful utility spell into a disgusting weapon in it's own right. Ever imagined what would happen if Byakuya applied this spell to his Senbonzakura? What about Senbonzakura Kageyoshi? The power of this spell should immediately become apparent, even without being applied to things like that, it still has the power to change the outcome of a fight all by itself. As previously stated, I've won many battles with a single well-placed Kyokkō spell.
- Purpose: One of the easiest spells to cast by far, it's also most likely frequently used. It's effect is immediate, requires only line of sight to the target and can be performed with a simple gesture. It's an easy spell to master, and a very useful one. But contrary to what you might believe, it's power doesn't lie in it's ability to bind the target, no, the binding strength is probably too weak to bind anyone of real significance on it's own. At best it might provide a brief lapse for you to prepare a stronger binding spell, but don't count on it. No, the primary use of this spell is a defensive one. Imagine the following scenario in your mind, a Zanjutsu specialist and a Hakuda specialist each attempt to strike at you, but then you respond by casting Sai. What happens? You've effectively countered their attack and if they were caught by complete surprise, left them wide open for a counterattack.
- Comments: Because Sai is such an easy spell, mastering it to the degree you can cast it silently should be achieveable for most Kidō Experts, although it would indeed require much training. Casting spells silently is usually master territory. Keep in mind that this spell isn't easy to break, because there's no physical restraints created, it's more like a forced condition, an enchantment. Unless you happen to be very proficient in Kidō it's unlikely it's effects would much impede a true master of Hakuda or Zanjutsu, although you might manage to change the angle of their attack enough to evade an otherwise fatal blow. As for improvements, imagine if you could target other things than their arms?
- Purpose: Killing. That's basically the gist of it, when you cast a spell like Haien, which causes complete and utter incineration upon contact, you're not interested in asking questions. When cast by a novice, Haien is the kind of spell that'll cripple you, burning away flesh and bone where it hits, when cast by a true master, a direct hit from Haien causes immediate death. You don't want to take this spell head on, you want to evade it or deflect it somehow. There's not really muh to say beyond that, other than this being a spell that'd likely be favored by assassins. Cast Kyokkō to conceal yourself, move silently behind the target and cast Haien. Not only does the target die immediately without the chance to scream for help, but it also removes any evidence. Victims killed by a well-executed Haien spell likely go missing, never to be found again.
- Comments: Obviously, the killing power of this spell is it's focal point. Because it's power is so high, it's the kind of spell you might want to use to literally scorch through your enemies defenses. Because of the intensity involved in casting this spell though, I'd say that it's not exactly cheap to cast. Haien can be improved in many ways, but it'd take a master to do so to any large degree, at most I could visualize a basic change of shape by a Kidō expert, but that's about it. If you wanted something more than that you'd need to have master-level proficiency in Kidō .
- Purpose: Ahh, the typical Kuchiki spell. If I were to name the most immediately effective binding spell of them all, I'd be inclined to name Rikujōkōrō. An upper-ranked mid-level spell, Rikujōkōrōs primary function is lockdown, and the way it does this is very effective. It's a spell that appears around the target in a perfect circle, converging inwards towards their body, leaving very little time for the victim to react, even as it limits their mobility and overall options. Rikujōkōrōs primary strength is that it seems to induce complete paralysis for a fixed duration, it's sudden appearance makes it the spell most likely to catch fast-moving opponents. Generally, if you're hit, this is the spell that's most likely to screw you over. Unlike physical restraints like Saju Sabaku, this spell doesn't care about your spiritual energy or physical strength. Once hit you become a sitting duck until it weakens enough for you to regain control.
- Comments: Obvious improvements would be to the reaction time this spell provides, along with extended durations. By having it manifest closer to the victim, while somehow retaining all of it's power your character could catch opponents they otherwise could not. Although, since Rikujōkōrō is a spell of moderately high level, modifying it to any large degree would likely require the talents of a master.
- Purpose: An easy to cast offensive spell whose primary feature appears to be it's sheer penetrative power and quick execution. If there's a cink in an opponents armor, or if a Shinigami finds themselves in need of damaging an Arrancar through their Hierro, this is the spell they're going to cast. By focusing high-density energy on a single point, it allows a Shinigami of low power to deal significant damage to more powerful Hollows, and as I mentioned, Arrancar. It can also be utilized as a killing spell, because as it travels quickly and possesses great density, Byakurai could be aimed at vital organs and fired with remarkable accuracy. Another likely favorite of assassins, as it's range appears to remarkable as well, allowing for sniping.
- Comments: Like most low-ranked spells on this list, Byakurai's simplicity makes it comparatively easy to modify, and it too could likely be completely mastered by an Expert. Thus far it seems that it can be manifested either as multiple smaller projectiles fired in quick succession, as a narrow beam with high range and penetrative power, or as a continous beam of energy maintained from the index finger over the course of a few seconds. Functioning as something of a makeshift laser. In the last case, it functioned more like a slashing semi-blade of lightning than an actual beam. Having enough power to cut through solid stone.
- Purpose: This one is a bit more obscure, but it's purpose is rather obvious. It's obviously there to make sure you get to where you need to be in time for that job interview that starts in five minutes. Jest aside, Sentan Hakuja is the kind of spell that'd be immensely useful for any officer to have, in particular a Lieutenant. It doesn't seem to be widely known, but the fact that it's capable of transporting everyone inside it's borders to a place of the casters choosing makes it extremely powerful. Even moreso because it doesn't require a willing subject either, everyone within the borders will be transported without fail, another Omnitsukido favorite, I'd wager. The uses? Kidnapping, transporting powerful individuals to key positions, entering battles from afar, getting to that job interview I mentioned earlier, taking a much deserved vacation without bothering with those pesky trains and airplanes. I'll stop.
- Comments: This is the kind of spell that can enact change, and change is power. In other words, with Sentan Hakuja you can make or break a war, you can quickly defend key positions, and you can quickly remove enemy commanders from the fight by taking them elsewhere, like a prison. It's only limitations are the need of a material component, the length of which likely determines the radius of the teleportation and that it's range seems to be finite. These are all limitations which a dedicated Kidō Master could correct, if given the time. I think this spell is a highly advanced one though, Aizen and the others likely stole it from the Kidō Corps, given how most of the Gotei 13 seemed very unfamiliar with it. At least I hope they were unfamiliar with it, otherwise they could abuse it against the Quincy by ganging up and destroying one target at a time, working through their ranks. Oh Kidō , why are thee so understimated!
- Purpose: Like with Haien, this is a pretty simple one. Incapacitation. Essentially, if you're struck by Hakufuku, you'll either be very unfocused if you only caught a passing glance, or outright knocked out, if you took the spell head on. From whats been shown thus far, the spell appears to put the victim into a state of suspended animation, making them appear dead to all senses. Ahem, another Omnitsukido favorite, that much is for certain. As well as a spell that likely has it's many tactical uses.
- Comments: This is one of those spells that can have an immediate effect on the subject, in the sense that it can immediately end a fight. Even if your opponent does not fall prey to you, that means they're not looking straight at you, and that forces an advantage in your favor. Since Hakufuku has such a powerful effect already, it'd be difficult to modify by someone not devoted to the art, but an immediate improvement would be if merely looking at you would be enough to deliver it's full effect. This would essentially force your opponent to fight with their eyes closed.
- Purpose: This spell is a form of pre-emptive protection that's typically referred to as a ward. It's a type of spell which is cast before combat to protect ones weak spots and allow for more aggressive behaviour, if you still recall any of what I wrote earlier, spells of this nature is the specialty of many Battle-Mages. While most wards function more like magically-recreated Hierro in practise, this one is unusual in how sophisticated it is, it's not the kind of ward that can be torn by simply using a high-powered attack, far from it. Even if Ichigo did don his mask before striking Aizen, the result would've been the same. See, from what I could infer about how the spell operated, it doesn't block the attack as much as it disorganizes and deflects it.
- Comments: This is master-level stuff, the sheer amount of variables involved in creating a spell of this magnitude is huge. There's not that many ways to improve upon this spell, although a true master of the art could potentially modify it in order to ward entire areas, as opposed to a single point their body. But this would be situational at best. I'd like to say however, that Millón Escudo is without a doubt the single most advanced protective spell shown in canon. At least until this point. There'd be few Shinigami capable of casting it successfully, wards as a general rule are dependant on contingencies, which are very difficult to form even for ordinary wards, a ward this sophisticated would be beyond the grasp of most.
- Purpose: There's a wide degree of elements involved in Kidō , Tenran is unique in that among the spells revealed thus far, it's the only spell which summons wind. The applications of this particular element are extremely broad. It's a mid-level spell with many uses, with this it's easy to deflect thrown projectiles, disrupt an opponents battle style. Counter multi-directional attacks such as Senbonzakura and it's more powerful Bankai, throw other techniques off-course, damage opponents by the sheer impacts and naturally, to create distance between you and your opponent.
- Comments: An extremely diverse spell, Tenran could be modified to produce things like swirling barriers of air, whether they be wind walls or spherical fields around the caster. Refined blades of pressure, powerful projectiles that explode with great concussive upon impact. It'd require the hand of a master of course, but it's sheer versatility marks it as deceptively effective even in it's unmodified state.
- Purpose: This is the sealing spell that eventually defeated Aizen, and most likely the most powerful seal devised over the course of the original storyline. Similar to a ward, this spell only fully activates under certain conditions, that being that it's host is weakened sufficiently enough for this to be effective. Ichigo was in the end little more than an unwitting pawn to weaken Aizen enough for this spell to set in. But then it's fairly obvious that the entire story can safely be summed up as a duel between these two geniuses, Ichigo just so happened to be the main piece in their century-long game of chess.
- Comments: Another master-level spell, whaddya know. Like with Millón Escudo this is another spell that'd require many variables, seals as a whole are highly advanced Kidō rarely taught to the Gotei 13, judging by the fact that thus far, there's not a single sealing spell among the main branches of Kidō utilized by Shinigami. The reason I'm mentioning spells like this and Millón Escudo is largely because they help explain some underlying elements of Kidō , because by and large explaining these won't really help your typical Shinigami character that much.
Concluding[]
That ends my guide, at least for now. I'll probably add more sections in the future, when I think fo them, feel free to post your ideas and such in the comment section, as well as any criticism. If you don't agree with my take on Kidō , that's fine of course. I'd love to hear the opinions of others, I might even make a section devoted to that too! Make sure to provide feedback in either case, if you liked this guide, don't hesitate so say so.