Uth'Bal, Chaos Savant

At the beginning of combat on your turn, flip
a coin until you lose a flip.
Repertoire - Whenever you win a coin flip, you may conjure a card from Uth'Bal's Repertoire.
{t}: End your turn. (Exile all spells and abilities
from the stack. The player whose turn it is discards
down to their maximum hand size. Damage wears
off, and "this turn" and "until end of turn"
effects end.)