Its a 6/6 for 6, and it lets you find two other cards from your decknot named Burning-Rune Demonand put one, which and opponent chooses, into your hand and the other in your graveyard
In the late game stages of a match in Commander or another game format, it allows you to summon a creature of your choosing, provided you know the cost of said card
but the protection comes in real handy
If you have opened your fair share of packs from the set, you might have a good number of uncommon cards hanging around waiting to be played with
But if your mutated creature is flickered and returned to the battlefield then all of your mutations come back as their own creature rather than as the pseudo-aura they once were
Take Tendrils of Agony for example, it would take a storm count of 10 to reduce a person from 20 life to 0