VERY nice card.
I think it would actually work better if you're allowed to use spells like RoF and Plague on your own side of the field. You could use this with Plague and Boneyard to get a couple of fast mutants, then after you spawn Skeletons out, you can use the Mutation spell on them.
However, as of right now, you can't use these spells to target yourself, so this creature card simply becomes a card that no one really wants to kill.
Interesting idea, and great work as always.
And I am LOVING this artwork.