Vol'tah'x, Nightmare Archive

Deathtouch, Mutate 1{w/b}{u}{u}
Whenever Vol'tah'x mutates, exile any number
of permanents you control, and return them
under your control. You may also exile one
permanent an opponent controls, and you may
return under their control. Any mutated
creatures returned this way remain mutated.
—
Some nightmares have a purpose, a lesson. Vol'tah'x
just cares that they are persistent.