Gax, Coalition's Exile

Menace, First Stike, Deathtouch, Ward {3}
Whenever ~ deals combat damage to an opponent, search that opponent's library for any nonland card with mana value X or less where X is the amount of comabat damage dealt by ~, and exile it. Until end of turn, you may cast that card without paying its mana cost.
Gax, Coalition's Exile can only be your commander