Mak'Thul, Tyrant of the Vents

Flying, haste
At the beginning of combat on each opponent's
turn, put a +1/+1 counter on Mak'Thul, Tyrant
of the Vents if that player cast a spell this turn. Otherwise, untap it.
Blitz (After each opponent's first combat phase on
each of their turns, you have a combat phase. Only creatures with blitz can attack during that combat
phase.)