Nesferet, Fist's Pilgrim

First Strike
Sovereign -- Creatures you control get "As long as you cast an instant or sorcery spell this turn, this creature gets +1/+0 and first strike until end of turn."
Whenever you cast an instant or sorcery spell, you may exile Nesferet, Fist's Pilgrim. If you do, return him to the battlefield under your control and draw a card at the beginning of your next end step.