Harpoon Sniper

A repeatable pinger whose damage scales with how committed you are to a single tribe, which is a rarer build in white than it sounds: most repeatable damage this color offers is fixed and cheap, while this one grows with board presence and asks you to keep Merfolk alive to keep it lethal. The activation only hits attackers and blockers, so it cannot pick off a mana dork or chip at a planeswalker; it is a combat tool, built to win exchanges in the red zone rather than govern the whole board. That restriction is the tax that keeps a tap-and-shoot pinger from being oppressive in a tribal shell: it has to wait for combat, and the damage is only as large as your Merfolk count. Because this card counts itself, the floor is one damage even when it stands alone, but the ability scales up fast once lords and tokens fill the table. The tap cost shapes its tempo more cleverly than it first appears: you can declare this creature as a blocker, then tap it mid-combat to shoot a different attacker, soaking one body while killing another. Run alongside enough other Merfolk and the math turns ugly: a handful of bodies converts a single white mana into a recurring removal spell that resets every turn, killing blockers before they can trade or punishing anyone who swings in. It is a payoff that wants a full tribal commitment and pays it back with a slow, grinding inevitability in the combat step.