Briar Hydra

Domain rewards the greedy manabase, and this Hydra converts that greed into a snowball once it connects. The counters do not stay home: the trigger targets a creature you control, so a clean hit can either dump the whole pile onto a stalled one-drop to make a second threat that dwarfs the Hydra, or fold them back onto the Hydra itself to make the next swing hit harder. That target choice is the design wrinkle that separates it from the usual "grows when it attacks" green fatty: the reward is portable, and where it lands is a real decision. Underlying it is the tension baked into every Domain payoff, which wants two things at once: a manabase stretched wide enough to count the full spread of land types, and combat damage getting through in the first place. Trample solves the second problem. It forces damage past chump blockers so the trigger actually fires, and it means the Hydra keeps connecting even into a clogged board, feeding the engine turn after turn. The ceiling scales with how many land types you assemble rather than with your spell count, a slower and more deckbuilding-dependent axis than most counter payoffs run on: you pay for the domain count in your mana development long before the Hydra ever swings. Even alone, it is a legal target for its own ability, so a single unblocked hit off a fully developed green ramp shell turns a stalled game into a fast clock.