pf2e.fyi
From Pathfinder Lost Omens Shining Kingdoms, which isn't enabled.

Opportune Opening

FEAT 10
ARCHETYPE
Activity reaction
Archetype Blackjacket
Prerequisites Blackjacket Dedication
Trigger An ally lands a critical hit on a creature within your melee reach.

Your combat training taught you to capitalize on any moment of weakness from your foe. You make a melee Strike against the same creature your ally just hit. The creature is Off-Guard against this Strike

Pathfinder Lost Omens Shining KingdomsORC