What this allows you to do with Myrkul on the battlefield is put enough -1/-1 counters on these Creatures to put them into your graveyard yourself, then choose to have them come back as Enchantments
While Craft has some additive abilities that can cause confusion, and Descend or Descended really feels like three different keywords mashed into one, the new MTG Discover mechanic is definitely the most complex of the three at least, without additional context
Unfortunately, as a Commander, Brimaz, King of Oreskos will limit you to only playing white, meaning youll miss out on some of the strongest cats around such as Feline Sovereign
The first official mutant was Mistform Mutant in Onslaught , although Goblin Mutant from Ice Age was mutated (erratad) with the creature type mutant later on
Nemata, Primeval Warden Saprolings are an archetype thats all about sacrificing the tokens, and Nemata, Primeval Warden is the best commander for this