There is a Legacy version
here.
Arcane Countermeasure
[reaction] Focus 5Uncommon Focus Manipulate Sorcerer Source Player Core 2 pg. 265Bloodline imperialTrigger A creature within range that you can see Casts a Spell.
Range 120 feet;
Targets the spell cast by the triggering creature
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.