Safe Passage

Green's Fog stops all combat damage by saving attacker and defender alike; this one is partisan. It draws a line through the battlefield and protects only your side: your life total and your creatures walk away clean, while nothing stops your blockers from killing whatever swung in. That one-sidedness is the whole design argument. A symmetrical damage-prevention spell is a stall that buys a turn; a directional one is a combat trick that turns a profitable attack into a slaughter, because the defending player blocks freely, deals lethal back, and takes none of the return fire. The two generic mana and the white pip are what you pay over a one-mana green Fog to keep the prevention pointed one direction. White has long owned the prevention shield as a defensive idiom of its own, distinct from green's combat-step bluffs, and this is one expression of it: not a wall, not removal, but a held instant that rewrites the math of a single attack the moment damage would be dealt. Because it prevents all damage to your side rather than just combat damage, the same held card answers a burn finisher or a damage-based sweeper aimed at your board, blanking a lethal Pyroclasm as readily as an alpha strike. The catch is the turn clock: prevention lapses once the turn does, so the window it buys is exactly one turn wide and gone the moment your opponent passes.