Arcane Countermeasure

Trigger A creature within range that you can see Casts a Spell. You undermine the target spell, making it easier to defend against. You reduce the spell's rank by 1, and targets of the spell gain a +2 status bonus to any saving throws, skill checks, AC, or DC against it. You can't reduce the spell's rank below its minimum. For example, a 5th-rank Howling Blizzard would remain 5th-rank, but a 5th-rank Fireball would become 4th-rank. Targets still gain all the other benefits, even if you don't reduce the spell's rank.