Heavy Ballista

The defensive pillbox in a color that does not usually get to point damage at will. The combat-only clause is the whole design: it only hits attackers or blockers, so the ability is dead outside the combat step and lives entirely inside it. That is exactly what lets white have a repeatable two-damage pinger at all. It cannot snipe a planeswalker, cannot ping a player, cannot pick off a mana dork on the draw step; it sits back, taps, and turns every attack into an arithmetic problem for the opponent. A 2/3 body that taps to deal 2 trades up against most early aggression while staying home, and the restriction keeps it from being the kind of unconditional removal engine white is structurally denied. It belongs to the small family of "ballista" creatures that gave white and red board-control tools framed as artillery rather than spells, the design idea being a creature that functions as removal you have to defend rather than removal you cast. The flavor and the function line up cleanly: a fixed emplacement that punishes anything walking into its arc and does nothing the moment the fight moves elsewhere.