Nethroi, Apex of Death

Mutate was pitched as a tempo mechanic: stack a creature onto another and inherit the pile's abilities. This one weaponizes the trigger instead, turning the act of mutating into a mass reanimation clause capped at ten total power. That number is the whole design lever. Ten power is not one big threat; it is a spread, which means the card wants your graveyard stuffed with efficient bodies (mana dorks, sacrifice fodder, deathtouch blockers, aristocrat triggers) rather than a single haymaker to loop. The reanimation is not locked to the first cast, either: because mutate needs a non-Human host you already own, every subsequent mutate onto that same pile fires the trigger again and refills the graveyard raid, so long as a legal host sits on the board to receive it. That host requirement is the quiet tax on the whole plan; with nothing to mutate onto, the five-mana lifelinking deathtoucher is just a body, and the recursion engine sits idle. The deathtouch and lifelink stay bolted to the mutated pile itself, not to the reanimated crowd, which is why the card gets built around for the trigger rather than the keywords: those creatures return as whatever they were, so the payoff lives entirely in choosing what fills the graveyard. The Cat Nightmare Beast frame is flavor; the mechanic is a reanimation payoff wearing a mutate creature's skin, and the ten-power ceiling is what keeps it a builder's puzzle rather than a two-card loop.