Benjamin Tennyson

It started when an alien device... (You can have
two commanders if the other is an Omnitrix
Legendary Artefact. If so, this card's colour identity includes all colours).
Whenever this creature mutates, create one
mana of any of this creature's colours.
Whenever this creature unmutates, you may
discard an Alien card. If you do, return a
different Alien card from your graveyard
to your hand.