Mega Malamar

Terastallize

Mind Control — During your end step, exile the
top card of each opponent's library. You may play
those cards for as long as they remain exiled. If you
cast a spell this way, you may spend mana as if it
were any color to cast it.

Foul Play — Whenever a nonland permanent
enters under your control, put a -1/-1 counter onto
a target creature.