Sileeris, Bloodline Stealer

Mutate {2}{w/b}{r}

Whenever Sileeris, Bloodline Stealer destroys a nonartifact creature, you can have that creature Mutate {x} under him, where X is the destroyed creature's converted mana cost.

When Sileeris, Bloodline Stealer mutates, if he has mutated five or more times, transform Sileeris, Bloodline Stealer.