Senju Shinobi dies during the third Shinobi war and gets reincarnated as itama senju in the warring clans era with the skills Copy and devour. Also since it's his own skills he can't be controlled by the skills 
Copy: A copying ability that allows user to copy whole living or dead bodies and inorganic objects. The copied objects or copied people also completely copies all the abilities of the objects or people that was copied including chakra 
Devour: A ability that allows user to create a small black hole from there hand and just needs a small amount to absorb anything to gain its abilities, skills, techniques, appearance and chakra

Driven by his scientific curiosity and Tobirama's influence, Itama attempted his most dangerous experiment yet: Fusion. Using **Copy**, he summoned the spectral data of a Suiton specialist Senju and a Katon specialist Uchiha from his library. Then, using **Devour's** comprehensive principles, he didn't just use their jutsus—he tried to understand the chakra interaction at the moment of their clash.


In a controlled, isolated canyon, he had the two copies battle. As a fireball met a water dragon, he focused **Devour** on the point of collision, not on the matter, but on the *reaction* itself. Steam exploded, and with it, a flash of insight. He grasped the principle of vaporization, of heat transfer on a massive scale. It was the foundational step toward Storm Release. He didn't gain the bloodline, but he now understood how to artificially simulate its effects through precise, dual-nature chakra manipulation.


Chapter 19 - The First Fusion