pf2e.fyi
From Pathfinder Impossible Magic, which isn't enabled.

Shrink Spell

FEAT 6
Prerequisites Counterspell

You've learned to manipulate space to narrow the impact of other spells. When you use Counterspell to attempt to counteract a spell that has an area of a burst, cone, or line and does not have a duration, you reduce the area of the spell if you fail to counteract it. Remove 5 feet from the radius of a burst or emanation or 10 feet from the length of a cone or line.

Pathfinder Impossible MagicORC