Demigod of Revenge

The trigger fires on cast, not on resolution, and that distinction is the entire engine. Because the recursion clause keys off the spell going on the stack rather than the body entering the battlefield, killing the first copy in response does nothing to stop the chain: the others are already coming back, hasty and flying, the moment you announce the fourth one. Each subsequent cast resurrects every previous copy from the graveyard, so a deck running the full playset turns into a hydra that gets harder to clear the longer the game runs. Counter it, burn it, edict it; whatever falls into the graveyard is fuel for the next cast. The hybrid mana means it slots into mono-black, mono-red, or anything between, which kept the deckbuilding cost honest relative to the redundancy payoff. The body is fragile enough (a 5/4 dies to most removal that matters) that it never reads as oppressive in isolation, but the "cards named Demigod of Revenge" wording rewards committing hard rather than splashing one: the value scales with copies in a way few creatures of its era attempted. It is a self-reanimating threat whose insurance policy is itself, a closed loop that asks only that you keep drawing the same card.