Corrupted Resolve

The whole spell hinges on a single precondition that lives on your opponent rather than your own permanents: they must already carry at least one poison counter, or this counters nothing. That makes it a rare counterspell whose live-or-dead status is governed entirely by the opposing player's accumulated poison, not by anything on the stack and not by your own board, which can be empty when you cast it. The condition is a low bar (one poison counter is only a tenth of the way to a poison kill), but it is still a bar your deck has to clear before the card does any work at all. The reward for accepting that constraint is steep: an unconditional, two-mana hard counter with no "unless they pay" escape valve, the kind of clean denial that usually costs more or carries a drawback. The design is honest about its narrowness. It is a payoff card that asks you to have committed to the poison plan before it earns a slot, and it punishes opponents who treat a chip of infect damage as harmless. Outside that shell it is a dead card, which is exactly the point: a counterspell this efficient with no condition attached would be a far more dangerous design. This is interaction priced entirely in archetype commitment, a denial spell whose cost is paid in the poison your other cards have already dealt.