There are two different versions of this feat. Consult your GM to determine which is preferred.
The original version:
With your combination of combat and spellcasting prowess, you send otherworldly monsters back to their place of origin.
Benefit: When you confirm a critical hit with a slashing or bludgeoning weapon, you may cast dismissal or banishment on that target as an immediate action, and the target takes a –4 penalty on its Will save to resist the spell’s effect. You must have dismissal or banishment prepared or otherwise available to cast, and using this ability casts the corresponding spell.
The newer version:
Your familiarity with summoning creatures has taught you how to send them away with a well-timed strike.
Benefit(s): When you confirm a critical hit against a target while using Arcane Strike or with a weapon enhanced by your arcane pool, if the target was summoned by a spell you identified using a Spellcraft check, it must succeed at a Will save (DC = 10 + 1/2 your character level + your Intelligence modifier) or be sent back to its home plane as per the dismissal spell.
Pathfinder Player Companion: Blood of Angels © 2012, Paizo Publishing, LLC; Author: Amber E. Scott.
Pathfinder Player Companion: Monster Summoner’s Handbook © 2015, Paizo Inc.; Authors: Alexander Augunas, Tyler Beck, Anthony Li, Luis Loza, David N. Ross, Owen K.C. Stephens, and Linda Zayas-Palmer.