Sparren, Esper Champion

Flying

Creatures you control get +1/+1 for each artifact in your graveyard.

Whenever a creature attacks you you may surveil 1, If you do, the attacking creature
gets -X/-0 until end of turn, where X is
equal to the converted mana cost of the
card put into your graveyard. (Look at the top card of your library. You may put it into your graveyard.)