Forbidden Astral Basilica

Forbidden Astral Basilica, also known as Timeless Sacred Ritual is a technique developed by Zhuge Lian from the Weiß team. By using a chain of several binding spells and magical seals, plus a better enviroument for one to truly connect with its Sacred Gear, this technique was created to fully achieve Balance Breaker or, in some cases, other techniques beyond.

Summary
During his training with the Weiß Team over Winter Vacation in Volume 10, Ichijou Tsukino explains for said group that he wants to become stronger and better control the "evil" that tries to take over his own body, referring to the Juggernaut Drive curse. Surprised that his rival, despite the stories about Issei Hyoudou, still carries the curse, Elizabeth Albedo proposes that they try Forbidden Astral Basilica on him, despite the other's protests. She then asks for the barrier master, Zhuge Liang, to prepare them for the upcoming clash between ichijou and the rest of the Weiß Team, stating that they're now dealing with another Heavenly Dragon.

Abilities
Forbidden Astral Basilica is a chain of several binding spells and seals created by Zhuge Liang in order for one to better reach Balance Breaker. By putting the sacred Gear user inside of a chamber made out of magic seals, and binding them so they won't get out of control, Zhuge Liang them proceeds to merge both the user and the Sacred Gear in order for the former to better connect with it's sacred gear, synchronize it's emotions with it and finally reach Balance Breaker, in a process that might take hours or even days to occur. FAB apparently has also the possibility to unlock other techniques such as Breakdown The Beast and Juggernaut Drive within specific Sacred Gears such as Divine Dividing and Boosted Gear, both with dragons sealed inside of them, and either bring them up or seal them for good. However, such process takes a much longer period of time, and even with such strong barriers, others must enter the barrier in order to ease the rampaging user inside of it before it destroys the barrier and impose a threat to the surroundings. It is noted by both Elizabeth and Vali that the user, even if the achievement of Balance Breaker is a success, might sacrifice a few years of their own lifespam for it.

Drawbacks
Forbidden Astral Basilica do not unlock Balance Breaker right away, althought it helps the user achieve it with more ease. Also, for those who search to control either Breakdown the Beast or Juggernaut Drive, a timer will be put in one of the seals to put a time limit. If the time limit is up, the victim will be considered a failed attempt and as such, terminated on spot. There's also the risk of a complete Juggernaut Drive/Breakdown the Beast transformation, which is irreversible and as such, also deemed as a failure.

Forms
Forbidden Astral Basilica is a dangerous and powerful combination of several binding and sealing spells of ultimate class, developed by Zhuge Liang and separated in four stages:

First Seal: Five Pillars of Gautama
The first Seal: Five Pillars of Gautama(第一段階：釈迦の5つの柱; Daiichidankai: Shaka no itsutsu no hashira) is a basic yet powerful binding spell that summons from the user's hand five gigantic pillars of golden light that pins the victim to the ground with the strength of approximately 17,550 lbs (7,960 kg) each and reinfoirced with magical seals that stops, but don't harm, the Sacred Gear user. Despite being a powerful technique, Zhuge Liang states that it's only a distraction in order to hold the victim for a little longer than anticipated while Zhuge Liang prepares the other, stronger seals.

Second Seal: Four Beasts of Protection
The second Seal: Four Beasts of Protection(第二段階：保護の四神聖獣; Dainidankai: Hogo no Shiseijuu) is the second stage of Forbidden Astral Basilica formed by now four different seals with different effects each. By reciting four different mantras and gesturing four different hand gestures, Zhuge Liang is capable of creating four gates that together form a stronger barrier and allows the user to fuse with its Sacred Gear. This stage is separated by four different seals:
 * Gate of the Azure Dragon(青竜の門; Seiryū no mon): An enormous circular shield shaped like a dragon, it has the ability to create flaming rings from its sides in order to bind and control the victim.
 * Gate of the White Tiger(白虎の門; Byakko no mon): A line of white marble-like strips that creates around the user a box-shaped barrier in order to seal it within itself, leaving no ways of escape or colateral damage for the surrounding, controlling the overall power inside. Zhuge Liang, however, can open small passages from it in order to allow others to enter and try to ease up the sealed beast.
 * Gate of the Black Tortoise(玄武の門: Genbu no Mon): This seal takes the shape of six runes spread across the four walls, the ceiling and floor inside the walls of the Gate of the White Tiger, and it creates a gravitational pull that forces the victim to stay at the center of the box created by the previous gate.
 * Gate of the Vermillion Bird(朱雀の門; Suzaku no Mon): The final seal that creates a parasol-like seal from above the previous ones, and creates around it a barrier that both reinforce and reforms any damage done against the previous gates to an extend.

Third Seal: Deva Realm
The Third Seal: Deva Realm(第三段階：天道; Daisandankai: Tendō): it's presumely the final stage of Forbidden Astral Basilica, in which, from inside the complete second seal, Zhuge Liang creates several runes and holy symbols that destroys any form of individual mentality and power from within the seal and mixes them together, in such case, the user and its sacred Gear. By doing this, the user encounters and faces its Sacred Gear in it's rawest form, in a process that might take hours in order to successfully work. It is said by Zhuge Liang that in this stage the user and the Sacred Gear have a "heart-to-heart" conversation, and by sharing experiences and energy, they might reach complete understanding of each other's ambition and, therefore, Balance Breaker.

For those who want to reach beyond that, as in the likes of Breakdown the Beast or Juggernaut Drive, however, Zhuge Liang will put instead a timer of around 72-hours limit, in which one have to completely merge with the Sacred Gear and from within, battle the creature inside in order to obtain it. Since such techniques are much stronger than Balance Breaker, Zhuge Liang's seals are doomed to be unable to contain such power and, as a result, external help is needed in order to ease the best inside and maintain the barrier up.

Forbidden Seal: Nirvana
The Forbidden Fourth seal: Nirvana(禁断段階: 啓発; Kindan dankai: Keihatsu): It is a fourth stage of Forbidden Astral Basilica, discussed but for a nail not executed. The effects of such stage are unknown, but since Zhuge Liang was willing to use it when Ichijou's time limit was up, it is hinted that might be a fatal seal that kills the one sealed within.

Trivia

 * All the images are based on several Kido spells from the Bleach series. The process is also a shout-out to Ichigo's hollowfication training from the same manga.
 * The names of the seals are all based on several elements from chinese mythology and religion:
 * The first seal is named after the Tale of the Monkey King and Gautama Buddha('Shaka' in japanese), in which the former is unable to escape the latter's reach of hand, and is sealed under a mountain of rocks.
 * The second seal is named after the four sacred gears of Chinese astrology.
 * The third seal is named after the realm of eternal bliss, the Deva, in buddhism and Taoism.
 * The forbidden seal is named after the process of enlightment/Nirvana, in Buddhism.