Crater Elemental

Six toughness for three mana with zero power: the body is a stone wall that trades with nothing on offense and asks the rest of your deck to supply the clock. The two activated abilities are where the card actually lives, and they compete for the same card. The sacrifice line converts the wall into a four-damage removal spell, a clean trade-up that prices in the loss of the blocker; it costs you the body but rewards a deck that has already extracted value from six turns of chump-free defense. The formidable line does the opposite, temporarily setting base power to 8 and turning the wall into an attacker, but only when the creatures you control add up to eight total power. That count includes Crater Elemental itself, so a pump or an anthem effect on the wall can help clear the threshold rather than leaving the work entirely to the rest of the board. Still, the gating is the honest constraint here: the boost is available exactly in the games where you have already built a wide enough board to win without it, and largely absent in the grindy games where a surprise 8/6 would matter most. That mismatch is the recurring shape of formidable as a mechanic, expressed in one card. What carries it the rest of the time is the fallback: a durable early blocker with a removal spell stapled to the back, useful long before the payoff ever comes online.