Abomination

A 2/6 for five mana is a wall priced as a brick, costed around the static threat of its triggered ability rather than any pretense of combat math. The trigger fires on either side of the block, so green and white creatures cannot profitably attack into it and cannot profitably chump it either. With six toughness, the Abomination eats most of what those colors throw at it and drags the attacker into the graveyard at end of combat, sending a Serra Angel to the bin while taking nothing worse than a few points it can absorb. The "destroy at end of combat" timing is what holds the whole thing together: damage still resolves normally, so the green or white creature lands its hit before dying, which is precisely why the toughness is set high enough to survive a typical exchange and keep standing. The math only breaks against the genuine fatties: an 8/8 like Force of Nature deals lethal in the damage step and dies alongside it, a trade rather than a clean devouring. This belongs to the family of color-hosers the early game leaned on heavily, mechanical enmity dressed as flavor, the kind of answer later sets gradually retired in favor of effects that did not strand themselves against half the color pie. It is a creature built to make two specific colors regret committing to combat, priced and statted with no ambition beyond that.