pf2e.fyi
From Pathfinder #168: King of the Mountain, which isn't enabled.

Time Dilation Cascade

FEAT 20
Activity 3 actions

You borrow a bit of time from the future to act now. Make six Strikes. Your multiple attack penalty applies normally to these Strikes. If you successfully hit a creature with multiple Strikes, combine those Strikes' damage for the purpose of resistances and weaknesses. On your next turn, you regain 1 action instead of 3. This is before any alteration in your actions due to the quickened, slowed, and stunned conditions.

Pathfinder #168: King of the MountainOGL