Sometimes you want to immobilize, incapacitate or somehow defeat a foe in combat but you don’t want to kill him, and some games add complex mechanics to do that, while other doen’t add any mechanics at all.
Here’s an easy way:
- State your intention. “I want to immobilize him but not killing him”.
- Attack the enemy as normal, using non-lethal weapons or no weapons at all (punches and kicks might deal anything between a single point of damage to 1d4). When the target reaches zero or less hp, he’s defeated and you achieved what you intended to do.
If mid-combat you decide to try it, and the enemy has suffered damage from lethal weapons, you must use non-lethal weapons or your own hands from now on. But if the target reaches negative hit points, he’s dead, he only survives if he reaches exactly zero (then it’s a good thing to make punches and kicks deal only one point of damage, right?)
Of course, if you want to immobilize him so your friends can kill him, you have to use whatever grapple rules you have.
If you really need more complex rules that these, you know where to find your path to them, if you know what I mean.