Tsubasa activating his transcendent technique, Black Shunko.
It's were he uses Perfect Shunko in correlation to his Hollow powers. It is the one time he agrees to cooperate with his inner hollow(who's name is Shuyoku). In this state, like most transcendent techniques, his reiatsu becomes detectable only when he allows his opponents to sense it. His speed, strength and endurance are increased exponentially and he is capable of hollow techniques (Cero, Sonido, etc.)
However, since he is actually cooperating with his inner hollow, he does not lose control, and is as aware of himself as normally. He is also still capable of kido (on a much larger scale, though)
Such a state has fatal drawbacks, however. Perfect shunko requires that the user has a concentrated and focused flow of reiatsu. Any disruptances from a foreign being (even the user's zanpakuto) can result in fatal results. So, by forcing his hollow and this technique together, he risks great injuries, like shattering one's Hakusui and likely dying, or losing his shinigami abilities.
Anyway, I hope ya like (random background is random ^^)
EDIT: Fixed those abs, added smoke and redid the effects
Kuchiki Tsubasa ©