bumping this +1
The ability to make enemies surrender: would shorten long battles, relates to the (currently not-functioning-properly) ability to knock-out enemies, and all-around would make role-playing better as it would mitigate some of the harsh penalties for failing dialogue checks leading to combat. An "oops my bad, peace?" or "I don't want to go through the tedium of killing you" check.
For example, in the underdark there is a group of enemies who all gain the status condition "frightened" during combat
The kuo-toa when I kill their "God" (a redcap was tricking them into believing he was a god and got mad at me for exposing him)
This would be a perfect opportunity to make a intimidate check to end combat peacefully, but instead I'm forced to play out the entirety of the combat even though I'm basically guaranteed to win. Especially since I didn't want to kill these enemies in the first place, I just wanted to help! [see spoiler]
I'd suggest a persuasion or (str based?) intimidate check, with rules such as:
-It costs an action, so you can't just freely spam it
-The difficulty goes down slightly for every enemy you kill/knock out, and a lot if you kill a "leader" (it could start at DC 20+the enemy's level, making it unlikely to succeed without demonstrating your superiority first)
-Maybe it isn't possible for all combats. And/or it's only possible after you kill a leader (e.g., Minthara attacking the grove, my example above)
-Maybe you can only attempt it once or twice per combat. After a 2nd fail, the enemies refuse any additional attempts to talk.
Finally, this would also enable you to talk to NPCs that start out hostile: like the initial goblins attacking the Grove.