Infinite Dragon Engine

Infinite Dragon Engine, also known as Burning Dragon Blood Circulation, is a combination technique used by Ichijou Tsukino in Highschool DxD: Яe-birth. By combining the boosting properties of his Level Zero technique and the Boosted Gear's [TRANSFER], Ichijou is able to powerup himself and his female partner for a combined attack.

Summary
This ability was first shown during the events of Volume 7 during the Miyama Runaway arc's climax. As a last effort to defeat Rei Miyama in his ultimate form and attack, Ichijou forced Ludger/Berolina to strip down and let him use Level Zero on her. Using her breast energy and using [TRANSFER] to boost her stats back, they were able to unleash a combined attack, Hellstar Red Princess Dragon, and finally defeat Rei in their spar.

This ability soon became Ichijou's trump card against more powerful enemies as long as he has a busty girl next him.

Abilities
By using the Boosted Gear's [BOOST] and [TRANSFER] abilities and his Level Zero technique, Ichijou is able to suck their 'Breast Energy' and double their power with his Boosted Gear, so that he can transfer it back to his partner at full power, both enhancing all of her stats back(hence the name) and Momentarily gives her some dragonic magical traits as well, making the attack even more powerful.

Just like in Level Zero, the bustier is Ichijou's partner, the better and stronger the Boosts and the transfer of power will be, as his combination with Ludger/Berolina unleashed a powerful attack that could counter the Golden Dragon in outrage mode.

Drawbacks
Much more like Level Zero as well, the bustier the partner, the more Ichijou will be able to extract power from, meaning girls with moderate chest size won't receive as much power as their busty counterparts would. Since it takes a few hours for the breasts to expand back to their normal size, there is also the weaknesses that it can only be used on a single partner once at a time.

Hellstar Red Princess Dragon
Hellstar Red Princess Dragon, also known as Crimson Dragonic Monarch who crosses the Universe, is Ichijou's combined technique with Berolina Gremory during her phase as Ludger Bael.

In his first time using Infinite Dragon Engine, he absorbed her breast energy then proceeded to boost and transfer it back to her, also passing some dragonic traits as well, unleashing an combined attack which takes the form of a massive, black and crimson dragon made out of pure power of destruction which seems to be semi-conscious, which pulverizes anything into nonexistence in its way, being strong enough to counter a Dragon King in outrage mode for several minutes.

Trivia

 * Hellstar Red Princess Dragon is based on a dragon from the Yu-Gi-Oh series.
 * The name of berolina and Ichijou's attack is in fact the combination of the names they chose for themselves in Volume 1.
 * So far, only Berolina was part/victim of this ability.