Ohmn, the Lightning Rod

Flash, Flying, Entice -- An opponent has cast 3
or more spells this turn.
When Ohmn, the Lightning Rod enters the
battlefield, exile all cards from graveyards that
were cast this turn. If Ohmn was enticed, put a
+1/+1 counter on it for each card exiled this way.
Counter the fourth spell played by each player
each turn. Whenever a spell is countered this
way, draw two cards.