Natra, Traitorous Usurper

{3}{w}: Destroy target attacking creature.
{4}{u}: Gain control of target creature.
{1}{r}: Exile the top card of your library. Until end of turn, you may cast that card.
Covenant - At the beginning of your upkeep, you may create a 5/5 black Demon creature token with defender and "At the beginning of your upkeep, you lose 3 life." If you don't, sacrifice all creatures you control.