There are two advantages to mutate commanders
Oona, Queen of the Fae Oona, Queen of the Fae is a nice leader for a faeries/flying token deck with a mill subtheme
You can get three creatures back from your own graveyard or from your opponents in a 1v1 game, but thats clunky at 6 mana, youll have more juicy targets in a 4-player pod, especially with mill decks
It is odd that it sets off death triggers and can be reanimated while the creature it turned into is still on the battlefield
Grishnkh, Brash Instigator If you build your deck around amassing orcs, Grishnkh, Brash Instigator could potentially be used for a very impactful turn when you steal a powerful creature
Every time I see it reprinted in a base set, it brings a smile to my face