Blizzard

A snow-matters payoff from the era that invented snow as a mechanic, and an unusually pointed one. The casting restriction (you need a snow land in play) and the cumulative upkeep tax are the two friction points doing all the balancing work: this is an enchantment that demands an ongoing mana investment, with each upkeep growing more expensive as age counters pile up, so it functions as a clock you run against yourself. What you buy with that escalating cost is a static lock on the air war: as long as this sits on the battlefield, flyers simply do not untap during their controllers' untap steps, so once they are turned sideways they stay grounded. That makes it a hate piece dressed as a global effect, aimed squarely at the decks that win through evasion. The specific method Green uses here is the design idea worth noting; the color has historically answered flyers with reach creatures and the occasional Hurricane, not with a static enchantment that switches off the untap step entirely. The snow restriction ties it to a self-contained subtheme rather than slotting it into any green deck, and the cumulative upkeep ensures it cannot sit on the table indefinitely without a payment plan. It is a narrow, expensive, beautifully literal answer: a blizzard grounds the birds, and you keep paying to keep the storm going.