Nemir

{u}{u}{u} Banishment- Put a Banish Counter on target creature, as long as Nemir is on the battlefield that creature is exiled.
{u}{u}{w}{t} Polymorph- Search your Library for a target creature, exile it. Nemir becomes a copy of that creature. When that token dies, Nemir returns to the battlefield.
{r}{r}{r} Search your library for a card named Lucifer, reveal it, and place it into your hand. Shuffle your library.