Whiteout

Green's license to answer fliers has never come through assassination; it comes through the environment, and this is that doctrine printed at its most literal. The base effect kills nothing and changes the sky for everyone, knocking the whole board out of the air for a single turn and resetting combat math before the air war resumes the moment the turn ends. By itself that is too narrow and too temporary to earn a card, which is precisely why the second line exists. Sacrificing a snow land returns it to hand, converting a one-turn weather change into a renewable anti-air tax for a deck disciplined enough to run snow-typed lands and patient enough to grind them away. That buyback is Ice Age's snow subtheme distilled: a payoff that costs nothing in the abstract and everything in deckbuilding, since the refund only exists if your mana base was built around it and you are willing to crack lands to fuel it. The shape of the answer reflects exactly how the color pie hands green this job: temporary, board-wide, symmetrical, more a shift in conditions than a piece of interaction. What remains is a standing toll on anyone attacking from above, refundable until the snow runs out and the lands stop coming.