Possessed Goat

A one-drop white body that pays a heavy toll to stop being one. The activation is deliberately expensive for what a 1/1 usually wants: three mana plus a discarded card is a real commitment, not a combat trick, and the "activate only once" clause means the transformation is a single burned fuse rather than a repeatable engine. What you buy is a 4/4 that gains black and Demon on top of everything it already was, so the payoff is less about the raw stat jump than about what the new type line unlocks mid-game: a creature that suddenly answers to black tribal payoffs and sits inside Demon synergies it had no access to as a plain Goat. Note that this is an in-game color and type shift only; the card's cost carries no black pips, so its color identity for deckbuilding stays firmly white. The discard rider does double duty, turning the ability into a graveyard-enabler as much as a growth spell: you can pitch a card you would rather bin than draw while you invest in the threat. The flavor tracks the mechanics cleanly, an ordinary farm animal that becomes something monstrous once, permanently, with no going back. It is a small piece of horror texture built around a single dramatic turn rather than an incremental value loop, and its interest lives in that irreversibility as much as in the stat line.