Radstorm

Proliferate on a Storm spell is a stranger idea than it looks, because the two mechanics measure entirely different resources. Storm counts spells: how many have been cast this turn, each cast adding another copy to the stack. Proliferate counts counters: the loyalty, the +1/+1s, the charge and experience and poison already sitting on the board. Stack them and you get a spell whose effect multiplies with your turn's tempo, so a fifth or sixth copy resolving after a busy sequence proliferates five or six times in succession. Each copy is a full proliferate, and each proliferate adds one counter of each kind already present, which is where the payoff hides: a single loyalty counter becomes a planeswalker's ultimate two casts later, a lone rad or poison counter snowballs, an infect line closes out of nowhere. The design tension is that proliferate does nothing without an existing counter to grow, so the payoff is entirely conditional on the board you've already built; the Storm count only compounds what's there, it doesn't create it. That makes this a build-around rather than a payoff, a card that asks for a counters-matter shell dense enough to justify a blue instant that lands late in a spell-heavy turn. The lineage is clear: counter-doublers and proliferate engines have circled this space for years, but pairing the effect with a scaling copy count is a genuinely new way to press on the same axis.