Hail Storm

A green Fog with teeth, and the asymmetry runs the wrong way. Where most defensive green tricks blank an attack at no cost, this one charges rent on both sides of the table: the 2 damage to each attacker is the payoff, but the 1 damage to you and each creature you control is the design tax that prices the effect. That second clause is what makes the card a puzzle rather than a button. You cast it knowing your own board eats a point, so it punishes a wall of x/1 tokens and rewards a board built around bodies that shrug off a single point. Green is the color least equipped to deal mass damage at instant speed, so the design hands it a sweeper-shaped effect and then claws back the symmetry that other colors' answers do not carry: white's wraths are sorcery-speed and total, red's mass-damage sweepers like Pyroclasm and Earthquake hit your own side too but are not reactive, and green gets a blast it can hold up and fire after attackers commit. The instant timing is the whole appeal, letting it ambush an all-in attack once the swing is declared and turn a profitable attack into a trade the defender dictates. It is built on the premise that green should be allowed to fight back, on the ground and in the air, just never for free.