Simic Transmogrifer

Flash
When you cast Simic Transmogrifer, destroy target creature. It can't be regenerated. That creature's controller puts a 3/3 green mutant token onto the battlefield.
Alter {1}{u}{u} ({1}{u}{u}, Discard this card: Search
your library for a creature card with power or toughness equal to or below this creature's, reveal it, and put it
into your hand. Then shuffle your library. )