Kren, the indestructible

+1: target planeswalker gains indestructible until end of turn. you may use this ability any time you may cast an instant
-2: Kren deals X damage to any target, where X is the number of instants and sorceries in your graveyard
-10: destroy any number of creatures. search your library for up to ten instants and sorceries and put them into your hand