For some reason today, a strange feat came to mind. It’s called Reciprocal Slaying, and it appeared on D&D writer Sean K Reynolds’ personal website in 2003.
The benefit is this: As a full attack action, you can allow an opponent to make an attack against you as if you were helpless. If it hits, it counts as a coup de grace – for reference, this means he automatically deals a critical hit, and you make a Fort save or die (DC 10 + damage taken). However, if it hits and you survive, you then get to make a coup de grace attack against your opponent in the same way.
Thinking back on it, this is a really terrible feat. It’s something you might use in an emergency, but not often enough to warrant a feat. It’s more of a “Book of Iron Might” manoever: a special attack with benefits and drawbacks that balance out but don’t require a feat to learn. I’ll blog more on those later, they’re interesting.
Imagine it in the hands of monsters, too. A kobold insta-kills your high level character. Or an undead uses it, because he’s immune to coup de grace.