Sentinel Tower

The math is storm-count math, resettable and pointed at a target: each instant or sorcery cast during your turn advances the meter, so the first spell deals one, the second two, the third three, and a spell-dense turn ends in a single large bolt. The floor of one damage on the opening cast is what keeps it from operating as a free pinger; the real payoff lives in the back half of a turn, once cantrips and rituals have stacked up to fuel one big finishing cast. Two design details give it more range than a pure combo piece. First, the trigger fires on any instant or sorcery cast during your turn, not only your own, so an opponent's instant-speed removal or a counterspell aimed at you still nudges the count higher and still fires the tower. Second, it cares about a spell being cast, not resolving, so a countered or fizzled spell feeds the meter all the same. Because the damage hits any target, the engine serves as both a creature-control valve and a reach finisher; because the count resets between turns rather than accumulating across the game, it rewards explosive concentration over slow grind. A deck that dumps six spells in a single turn gets far more from it than one spreading six spells across six turns. Where storm asks you to go off in one enormous burst or not at all, this offers the same escalating-count reward with a per-turn ceiling instead of an all-or-nothing one.