Mindleecher
{4}{B}{B}
Creature -- Nightmare
5/5
Mutate {4}{B} (If you cast ~this~ for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Flying
Whenever ~this~ mutates, exile the top card of each opponent's library face down. You may look at and play those cards for as long as they remain exiled.