Squall Line
Hurricane in instant clothing, with one structural change that matters more than it looks. The classic green sky-sweeper had always been a sorcery, which meant the player firing it telegraphed the math a full turn before resolution. Folding the same effect onto the instant timeline rewrites when the damage can land: it can be held until an attacker commits to the air, end-stepped to dodge a counter-window, or fired in response to a lifegain trigger to deny the buffer. The extra in the mana cost is the price that pays for the flexibility, since the symmetric X still feeds off your own life total as much as your opponent's, but instant speed lets you choose the moment when that exchange is favorable rather than announcing it on your own turn. Green has plenty of ways to interact with fliers and reach that hit the dome, so the card does double duty as a board reset against an aerial deck and a reach-style finisher that ignores blockers entirely. The lineage is worth naming: Hurricane and its blue mirror Flashfreeze-adjacent counterpart Whirlwind drew the template, and this is the version that asked what the same effect would do if it could be cast on an opponent's turn. The answer is that timing, not the numbers, is where the upgrade lives.
