Boosted Gear

Boosted Gear, also known as the Red Dragon Emperor's Gauntlet, is a Sacred Gear wielded by Issei Hyoudou. Listed as one of the thirteen Longinus, it has the spirit of the Welsh Dragon, Ddraig, residing within it.

Summary
In the past, Ddraig fought against his arch-rival, the Vanishing Dragon, Albion, in a battle that was interrupted by the Angel's, Devil's, and Fallen Angel's who were at war during the time. In anger, both Dragons attacked the leaders of the Three Factions, which led to their bodies being destroyed and their souls being sealed into two separate Sacred Gear's, with Ddraig moving into the "Boosted Gear", a Sacred Gear that eventually became one of the thirteen varieties of Longinus.

In Volume 9 of the Light Novels, it is revealed that when a host of the Boosted Gear dies, a fragment of their consciousness is stored inside the Boosted Gear normally only waking up during the activation of the Juggernaut Drive. However, there are two people who maintain a degree of consciousness; Belzard and Elsha. Belzard is known as the strongest Boosted Gear possessor for defeating two White Dragon Emperors in his lifetime, while Elsha is known as the second strongest and the strongest female.

In Volume 10, it is revealed that a past possessor of Divine Dividing was stored within the Boosted Gear when Issei used one of Albion's jewels to create the Dividing Gear. The past possessor of the Divine Dividing then used his halving power to diminish the dark thoughts of the Boosted Gear's past possessors, allowing Issei to awaken a power opposite to Juggernaut Drive: Cardinal Crimson Promotion, with a different chant.

In Volume 12, all the past possessors sacrificed themselves in order to save Issei's soul from Samael's curse.

In Volume 16, Euclid Lucifuge reveals that he created a replica version of the Boosted Gear by collecting information of the Sekiryuutei's soul and the Sacred Gear from Issei's original body that was left in the Dimensional Gap by using the Holy Grail. Unlike the original Boosted Gear however, the Boosted Gear Replica appears on the user's right hand with silver lining and uses the souls of famous Dragons to activate it. In the following Volume, the replica was destroyed after Euclid's defeat against Issei.

In Volume 18 Issei and Ddraig unlocked one of Ddraig's original powers called Penetrate that allows Issei to bypass defensive powers, such as Rizevim's Sacred Gear canceler.

In Volume 20, Issei uses a new chant that he and Ophis chant, alternating lines, that allows him to temporarily borrow Ophis' power of infinity. Ddraig names the new form Diabolos Dragon or DxD.

Appearance
Boosted Gear takes the appearance of a a red gauntlet with a green jewel and 2 golden spikes that manifests on the user's arm. In the anime, it's initial state looks like a regular Twice Critical. After a certain time, it transforms into a more Dragon-like gauntlet that covers up the user's hand and a majority of the arm. When the Boosted Gear reaches it's second liberation, it gains another green jewel and a total of 10 golden spikes, once again covers up more of the user's arm.

Abilities
The Boosted Gear has the ability to Boost which can double the user's physical and magical power every 10 seconds. With further changes in response to the user's feelings, the Boosted Gear can transform into the Boosted Gear Gift, which has the ability to Transfer the increased power to other people or objects. The transfered power can be performed on multiple people/objects at the same time, however, this decreases the efficiency, and some of the power will be lost in the transfer. This can also be used on a certain part of the user's body such as the eye's for enhanced vision.

In Volume 3, Boosted Gear gains the ability to determine an opponent's power level and tells Issei when his boost has built up sufficient power to possibly defeat an opponent, either by utilizing it himself or transferring it to an ally. However, this ability has not been used since the fight with Kokabiel.

In Volume 4, the Boosted Gear has also been shown to be able to store powered weapons and items within it and allowing the user to wield their capabilities, such as the Holy Sword Ascalon (after some adjustments) and a jewel from Divine Dividing's Scale Mail. Storing the item is all dependent on the user's will

In Volume 18, Ddraig unlocked the power of Penetrate, this allows the user's attacks to hit, even through powerful defensive barriers. Issei soon adapted the ability to grant him the power to see through solid objects (i.e Clothing) at will.

In Volume 21, Issei unlocked the strongest of Ddraig's original powers, called Blazing Inferno of Fiery Flame.

Weaknesses
With Ddraig sealed within the Boosted Gear, its possessors become vulnerable to Dragon-slaying magics, swords and curses as if they themselves were Dragons. Also, continuous use of the Boosted Gear will drain the wielder's stamina to a significant degree.

Announcements

 * Dragon Booster: Summons the Boosted Gear.
 * Boost: Doubles the user's power. This call is announced every 10 seconds until the user reaches his/her physical limit. In Balance Breaker mode, this call is announced repeatedly until the user reaches his/her limit.
 * Explosion: Releases the Boosted Gear's stored power for a short period of time.
 * Reset: This announcement is called after all the Boosted Gear's stored power during Explosion is drained. Once called, the user cannot use Boost again for a certain period of time, so long as his body is not near its physical limits.
 * Burst: This announcement is called when the Boosted Gear's wielder reaches his/her physical limit. Once called, all of the user's increased powers are drained.
 * Dragon Booster Second Liberation: Changes the Boosted Gear into the Boosted Gear Gift. This announcement was used only once during the Rating Game between Rias and Riser.
 * Transfer: Transfers increased power to other people or objects.
 * Welsh Dragon Over Booster/Welsh Dragon Balance Breaker: Activates the Scale Mail armor, Boosted Gear Scale Mail. The first call was used in Issei's final showdown against Riser when he used an incomplete Scale Mail, while the second (and subsequent) call was first used during Issei's battle with Kuroka where he had attained his complete Balance Breaker.
 * Vanishing Dragon Power is Taken: This call was announced when Issei formed the Dividing Gear with one of Albion's jewels during his battle with Vali.
 * Divide: Halves the opponent's power. This call is announced every 10 seconds when the Dividing Gear is in use. In Juggernaut Drive, this call can be announced repeatedly.
 * Blade: Summons Ascalon.
 * Juggernaut Drive: Activates Juggernaut Drive.
 * Longinus Smasher: The chest armor of the Scale Mail slides open and fire a powerful shot. This attack was used only thrice in the series: in Volume 6 when Issei blasted Shalba Beelzebub while in Juggernaut Drive, in Volume 12 when it is used to completely blast away the last of the Jabberwocky, where Ddraig reveals that this is a forbidden and sealed attack, and in Volume 17 where, with the help of his Dividing Wyvern Fairy's boosting power, he was able to achieve it.
 * Jet: Allows Issei to fly with his Dragon Wings while in Scale Mail mode. Accessed after Issei entered Juggernaut Drive.
 * Change Star Sonic: Used in Illegal Move Triaina. Changes the Scale Mail armor into the Welsh Sonic Boost Knight.
 * Change Solid Impact: Used in Illegal Move Triaina. Changes the Scale Mail into the Welsh Dragonic Rook.
 * Change Fang Blast: Used in Illegal Move Triaina. Changes the Scale Mail into the Welsh Blaster Bishop.
 * Cardinal Crimson Full Drive: Activates Cardinal Crimson Promotion.
 * Bust: Announced whenever Issei touches Rias' breasts. This replenishes Issei's power and stamina, albeit at the cost of Rias' breasts shrinking with each use (though they do grow back to normal within a day's rest, according to Rias). This announcement is called repeatedly.
 * Star Sonic Booster: Used while in Cardinal Crimson Promotion. Grants the user godlike speed that far surpasses Welsh Sonic Boost Knight's.
 * Solid Impact Booster: Used while in Cardinal Crimson Promotion. Morphs one of Cardinal Crimson Promotion's fists into one of the Welsh Dragonic Rook's, allowing for an enhanced version of Solid Impact.
 * Fang Blast Booster: Used while in Cardinal Crimson Promotion. Fires the Crimson Blaster, an enhanced version of Welsh Blaster Bishop's "Dragon Blaster".
 * Reflect: It's one of the two abilities of Dividing Wyvern Fairy and the original power of Albion. The white dragons can reflect any incoming attack to a certain degree. It was first used against Euclid Lucifuge.
 * Penetrate: One of Ddraig's original abilities. Allows Issei's attacks to bypass defensive abilities, such as Rizevim Lucifer's Sacred Gear Canceller.
 * Blazing Inferno of Scorching Flames: The ultimate flames which can incinerate anything and can probably burn the soul, until nothing remains. Once ignited, they will never go out. Even Gods will be burnt to ashes within these flames. It was sealed by God in the Bible. It was only ineffective against Albion. However Ddraig mentioned it may also be ineffective against Great Red or Ophis. It is unlocked in Volume 21 due to the effects of Issei's second Dragon Deification.
 * Dragon Infinity Drive: Activates Diabolos Dragon
 * D ∞ D: Announcement called when Issei is directing Ophis's infinity power

Forms
Gauntlet=

Base Form: Twice Critical (Anime only)
The initial form of the Boosted Gear in the anime. It takes a form of a red, armored bracer with yellow accents and a green jewel on top of the palm area. The fingers aren't covered. It was initially mistaken as a Twice Critical.

Initial Form: Boosted Gear
The form where it was finally realized that it is the Boosted Gear. It first debuted during Issei's last battle with Raynare. It is a red, claw-shaped gauntlet with yellow accents and green inscriptions. It is also known as the Dragon Booster.

Upgraded Form: Boosted Gear Gift
Boosted Gear Gift, also known as the Gift from the Red Dragon Emperor, is Boosted Gear's third and final form in the shape of a gauntlet. It has the same appearance as the original Boosted Gear, except with a second jewel that grants the user the Transfer ability and that it covers more of the user's arm. It debuted during Rias' Rating Game against Riser Phenex.


 * -|Dividing Gear=

Dividing Gear
Dividing Gear, also known as the White Dragon Emperor's Gauntlet, is the Boosted Gear version of Divine Dividing. It debuted in Volume 4 during Issei's first battle against Vali, where the former placed one of Albion's jewels on his right gauntlet. The Dividing Gear resembles the Boosted Gear but is white in color, has a blue jewel instead of a green, and rests on Issei's right hand, as opposed to his left. With Dividing Gear, Issei gains all the powers of Divine Dividing. However, due to it consuming his lifespan, it was banned from use by Azazel.

Dividing Wyvern Fairy
Dividing Wyvern Fairy creates small dragons from the gems of his armor. It first appeared in Volume 16, replacing Dividing Gear. Originally, the Wyverns were only able to use White Dragon Emperor's powers of Divide and Reflect and unlike the Dividing Gear, this does not reduce Issei's lifespan. In Volume 17, Issei managed to change it so that the Wyverns could use either the White Dragon Emperor's powers or the Red Dragon Emperor's powers. The white Wyverns are able to use Divide and Reflect and the red Wyverns are able to Boost and Transfer. Whether the red Wyverns can Penetrate is yet to be seen. Issei usually uses the Wyverns to reflect his Dragon Shots around so he can attack his opponents from different directions, but he also uses them to boost his powers to the limit, allowing him to use the Longinus Smasher.


 * -|Balance Breaker=

Boosted Gear: Scale Mail
Boosted Gear: Scale Mail : Also known as the Armor of the Red Dragon Emperor, is the Balance Breaker of Boosted Gear which creates a Red Dragon Armor with green jewels that cover the user's body and strengthens its powers and abilities. When active, the user can double their power without the 10-second time limit, this also applies to later forms. The armor has two rocket thruster on it's back for a temporary boost of speed and flight, from them can come out a pair of retractable Dragon wings that enables the user for proper flight. Originally, it did not have wings, however, after Issei goes into Juggernaut Drive in Volume 6, it gains Dragon wings. In the third season of the anime, Issei's perfect Balance Breaker already has wings.

Juggernaut Drive
Juggernaut Drive : Also known as the Dragon of Supremacy, like Divine Dividing, Boosted Gear also has access to this form. This form unleashes the full power of the Welsh Dragon, but the user will lose their sanity and their life will also be devoured. Issei first went into Juggernaut Drive in Volume 6, which would also be his last time. It also has access to the Longinus Smasher, one of the most powerful attacks of the Boosted Gear.


 * -|Evil Pieces=

Illegal Move Triaina
Illegal Move Triaina is the enhanced form of Issei's Scale Mail, where the armor changes to various forms based on the Evil Pieces' traits.

The available forms for the Illegal Move Triaina are:
 * Welsh Sonic Boost Knight
 * Welsh Dragonic Rook
 * Welsh Blaster Bishop

Cardinal Crimson Promotion
Cardinal Crimson Promotion, also known as the True Crimson Dragon Emperor, is the Scale Mail's evolution of the Queen form. It changes the color of Issei's Scale Mail armor from red to crimson. Cardinal Crimson Promotion incorporates all three Evil Pieces traits, making it the most balanced and most powerful form of Issei's Scale Mail. It is Issei's answer to a power different from the Juggernaut Drive, making it at least as powerful as the latter.


 * -|Others=

Super Gigantic Balance Breaker
Super Gigantic Balance Breaker is the form that Issei takes after combining with Great Red in Volume 12. It resembles Boosted Gear's normal Scale Mail, except that it is incredibly enormous in size and now has access to the Longinus Smasher that was previously exclusive to the Juggernaut Drive.

Crimson Extinction Dragonar
Crimson Extinction Dragonar : A form developed for Rias, which is a combination technique between Issei and her. Issei uses his Red Wyverns and sync both of their auras while the Wyverns attach themselves to Rias to create her own female variation of the Scale Mail. The armor acts just like the original, strengthens Rias's abilities and giving her the ability to utilize Boost, Transfer, and Penetrate until she reaches her limit.

Crimson Destruction Dragonar
Crimson Destruction Dragonar (クリムゾン・エクスティンクト・ドラグナー, Kurimuzon Desutorakushon Doragunā): Xenovia's own variation of the Scale Mail armor, which she gained by also synchronizing her aura with Issei's to use his Red Wyverns to attach themselves onto her body which shifts into the form of armor. Like the original, it has all of the same functions of Boost, Transfer and Penetrate. This is noted to be similar to Rias' and yet different.

Diabolos Dragon
Diabolos Dragon : Is a new form Issei gained in Volume 20 from tapping into Ophis' power inside him. This is due to the fact that his body is made from Great Red's flesh, which enables Issei to temporarily borrow Ophis' power. In this form, the armor becomes "organic" changing the armor's shape, and the armor's color changes from pure crimson to a mix of crimson and black. Additionally, this form gains a total of four wings, each one containing a cannon. Two of the cannons are over his shoulders and the other two are under his arms. In this mode, the Boosted Gear's announcement voice becomes an amalgamation of Ddraig and Ophis's voices and instead of "Boost", the Boosted Gear announces "D∞D" as Issei directs Ophis's infinity power. Diabolos Dragon grants Issei Ophis's power of infinity, enhancing him to the point at which he was able to easily overwhelm Rizevim Livan Lucifer, overpowering his Sacred Gear Canceller. Diabolos Dragon's finishing move is the Infinity Blaster, a powerful aura blast in which Issei directs Ophis' power to the four cannons stored in the armors wings, then fires them. The Infinity Blaster is so powerful that the blast left Rizevim injured to a extent that his body is almost fatally damaged. According to Rizevim, Diabolos Dragon has similar features to the Juggernaut Drive without the ominous aura. However, the time Issei can spend in DxD mode is very limited, and after the armor is released, Issei experiences immense pain throughout his entire body and becomes comatose.

Issei and Ophis alternate lines when chanting the Diabolos Dragon chant.


 * Issei: "I The Crimson Red Dragon dwelling within me, awaken from your dominance"
 * Ophis: "The Crimson Heavenly Dragon I possess within me, rise up to become a King" 
 * Ophis: "The jet-black God of Infinity"
 * Issei: "The glorious Red God of Dreams"
 * Both: "Watch over the forbidden existence we shall become that transcends the boundaries"
 * Both: "We shall dance like radiance within the inferno!"

Following Issei's battle against Apophis, Ophis adjusts the D×D to prevent the severe backlash of that form and is subsequently renamed the D×D・G in tandem with Vali's D×D・L. In Volume 22, a modified version of chant was used by Issei.

Trivia

 * In the anime, the Third Form: Boosted Gear Gift had an additional four golden spikes in the upper part of the gauntlet and two on the side of the wrist whereas in the manga, which follows the light novels, the six golden spikes aren't shown.
 * In the anime, using Boosted Gear Gift appears to cause a pleasurable sensation in females whom the "Gift" is given to.
 * Cardinal Crimson Promotion is modeled after the ZGMF-X10A Freedom Gundam from Mobile Suit Gundam SEED. The Diabolos Dragon's Infinity Blaster is very similar to the Freedom's Full Burst attack.
 * In the Afterword of Volume 12, the author stated that Super Gigantic Balance Breaker is a special form for this volume only.
 * Longinus Smasher and Super Gigantic Balance Breaker appear to be homages to the Mega Smasher and Gigantic Exceed of Guyver.
 * In Episode 11 and 12 of the anime's second season, Issei demonstrated the ability of extending the blade far longer than it's normal length, whether this is a normal ability of the sword or an ability gained with the fusion with the Boosted Gear is not clear.