Idea for shuriman champion

HEAR ME OUT. A champion (maybe a martial artist) that transforms into a feral beast after dealing a set amount of damage to a champ. The transformation increases attack speed, move speed, and puts majority of bonus hp into AD. His/her abilities get enhanced, but changes back after a kill or death.

To make this unique, they could transform into a void spawn. But, that means the champ itself would have to be shuriman, maybe icathian