From Pathfinder Impossible Magic, which isn't enabled.

Weighty Impact

FEAT 10

Prerequisites Your eidolon has an unarmed attack with the shove or trip trait

Your eidolon hurls enemies to the ground or across the battlefield. Choose one of the eidolon's unarmed attacks that has the shove or trip trait. The attack gains the other trait as well, and your eidolon gains the Knockdown and Push actions for that attack.

Pathfinder Impossible MagicORC