Loathsome Catoblepas

The death trigger is the whole transaction: when this dies, an opponent's creature takes -3/-3 until end of turn, which turns the 3/3 body into a delivery mechanism rather than a threat. The card wants to die, and it pays you for trading or sacrificing it instead of keeping it alive. The green activation is what shapes the removal into something you can aim: for you compel the Catoblepas to be blocked this turn if able, a lure-style compulsion pulling a defender into a creature that carries nothing to win the fight but a lethal parting gift. That green splash on a black creature lands the design squarely in Golgari, pairing forced combat to a subtraction effect. The compulsion is not a guaranteed kill: an opponent with no legal blockers is free to take the hit, and a blocker large enough to survive the -3/-3 will simply eat the 3/3 and walk away. But when the trade lands, it can drag two creatures down at once, one dying in combat and a second withering into the graveyard after the trigger resolves. That is the quiet ambition here, a double-removal pattern hidden in a beast. Played straight, the Catoblepas is a six-mana body attached to a removal spell, with an optional button to point the death where you want it, and a green activation that costs you tempo to make the black payoff detonate on schedule.