Star Rage

Star Rage is Yuki Tsukumo's innate technique that allows her to add virtual mass to herself and her shikigami, Garuda.

Description
The primary function of Star Rage empowers its user with the ability to add mass to themselves and the shikigami associated with this technique, Garuda. The mass added is virtual or imaginary, but it bolsters the user's physical attacks with force equal to the real mass assigned to them. This also applies to Garuda, which becomes a cursed tool for the user to wield.

The user can use this technique to imbue themselves with virtual mass capable of bolstering their physical attacks with force equal to the mass assigned to them. The only other thing affected by Star Rage is Garuda, a shikigami that becomes a cursed tool for the user to fight with while its empowered by the technique. The added mass doesn't weigh down the user but it doesn't or increase their body's tensile strength either.

These alterations only affect the user after they pass a certain density threshold. Adding titanic amounts of mass will condense their body into a black hole with extreme density and gravity.

Usage
Yuki's rank as a special grade sorcerer is due in no small part to her innate technique. She was so secretive about her ability that even Jujutsu Headquarters didn't possess details about it. Yuki mainly uses her Star Rage to improve her taijutsu prowess to indefensible levels, adding virtual mass to immensely improve every strike.

In her fight with Kenjaku, the curse user summoned Ganesha to target the concept of Yuki's technique. However, the concept of mass was so overwhelming that Ganesha was defenseless against Yuki's initial attack. Garuda folded itself into a ball and Yuki kicked it clean through Ganesha's head. She followed up with a straight punch empowered with virtual mass. Her strike pierced through the arms guarding Kenjaku's face, breaking them both in half. The impact sent Kenjaku flying so far that he punctured the circular definition of the empty barrier they were fighting in. Yuki confidently divulged the details of her technique while Kenjaku healed himself.

Star Rage's output was severely dampened by Yuki's injuries during the fight. While Yuki's body was severely damaged, Star Rage's effects weren't enough to properly weigh down Kenjaku when Garuda was wrapped around him. Her injured body also couldn't use Star Rage to a great enough effect to bring down Kenjaku with her physical attacks. Yuki remedied this by healing her injuries with reverse cursed technique, but this made Star Rage even more ineffective and allowed Kenjaku to escape Garuda completely.

Once healed, Yuki used Garuda as a whip and tore apart the environment with several high-impact strikes. She quickly cornered Kenjaku but he deduced that Star Rage didn't increase Yuki's durability and fatally wounded her. Yuki attempted to take Kenjaku down with her by continuously adding virtual mass to herself until her body transformed into a black hole.

Trivia

 * The Kanji reads "Star Rage" but the furigana reads "Bom-ba-ye", meaning "finish him". This is a famous chant from a match between famous boxer Muhammad Ali and George Foreman in 1974.