Ashtok, Castaway Phyrexian

Flying
Whenever activate an ability or cast a spell you
may exile Ashtok, Castaway Phyrexian, and return
him to the battlefield under your control. He gains
Haste. Put two -1/-1 counters on target creature.
Whenever a congestion of mana builds up, he is ripped
from his plane and transported to its origin. He has witnessed some of the most key events in history.