Bruce Banner, Genius Physicist

At the beginning of your end step, you get a rad
counter
{g/u}{1}, {t}, Remove X rad counters: Return target noncreature, nonland spell with mana value X or less
from your graveyard to your hand
{r}{r}: Bruce Banner deals 1 damage to itself
Enrage — When Bruce Banner is dealt damage,
exile him, and return him to the battlefield
transformed under its owner's control