Enemy’s Heart is an interesting little spell that lets you gain temporary hit points, a profane bonus to strength, and a bonus to caster level by performing a coup de gras on a helpless living target.
It has a full-round cast time. But I’m pretty sure it can made into Oil of Enemy’s Heart via Craft Potion.
So let’s say you have an Orcish witch with the Slumber hex whose Imp familiar carries a vial of Oil of Enemy’s Heart and a whetted sickle. You take your action to Slumber a nearby enemy; your familiar then swoops in as a move action and applies Oil of Enemy’s Heart as a standard action. As part of that action, it gets to perform a coup de gras.
Okay, an imp’s going to deliver a pretty crappy coup de gras. 1d3+1 x4 is only a DC 22 on average. That’s pretty easy to pump, though...every +1 damage from bard song or whatever adds 4 to the DC with a sickle’s modifier. Or maybe one of your party members would like be the designated annointer.
Applying the oil provokes AoOs, as does a coup de gras. Still, the ability to move and coup de gras in the same round is a nifty option.
The trick is a little pricey, 300g a pop...half that if your witch takes the Cauldron hex.
