Pistus Strike

Conditional removal that bolts a clock onto its kill. Green has always paid a tax to touch fliers, the color's structural blind spot, and the going rate is an instant that only answers the air: Plummet does exactly that for one generic mana less. The extra mana here buys a second clause that has nothing to do with the dead creature and everything to do with closing the game: the opponent banks a poison counter, a flat 10% of the ten-counter loss condition. That pairing is the whole pitch. The card is overcosted as pure interaction and useless as a standalone threat, but in a deck already counting to ten through infect creatures and proliferate, clearing a blocker or attacker while advancing the alternate win is two jobs in one card. The catch lives in the targeting: the spell has only one target, the flier itself, and the poison counter rides on resolution. If that creature slips out of range before the spell resolves (bounced, blinked, sacrificed), the whole thing fizzles and the controller takes no counter at all, which is the failure case to watch when the flier is the only thing standing between an infect attacker and lethal. Outside a poison shell the back half is dead text and the front half is a worse Plummet, which is precisely the trade the design is making: exactly right for one archetype, a tax everywhere else.