I do this with my regular players, but we had to set some ground rules about it (4th edition and 13th age have helped to cement these, but we were doing it in 3e as well). The ground rules are:Personally, I would probably leave it up to the players to describe what's happening when they attack or miss. Especially for weapon users for whom that's basically all that they do.
- I get to Yes And any description you make, and I get to include things that break the guidelines because I know how many hit points the monster has left and how their powers work
- I also get to remind you when you're breaking the guidelines and suggest an alternate description of what happened
- Unless I tell you it's a killing blow, you're not severing limbs or doing major damage - hit points aren't meat at our table for players or for monsters until you get down to 0 hp. If I tell you the monster is bloodied by the blow then you get to do a little bit of major damage (though no severing limbs or disembowelings unless for some reason it makes sense - the gutshot on a bloodied zombie for example).
- Unless you roll a 1, you didn't miss. You made a glancing blow or it bounced off their shield or they parried your blow coming in or you grazed them or something. It's up to you to describe what happens (the poorly named "miss damage" helps them keep this in mind, since they're almost always doing "miss damage" they remember that they're never outright wiffing).
- If you roll a 1, it's a complete miss. Feel free to narrate exactly how stupid your character looks, though unless there's a terrain effect or monster effect going on no matter what you describe you're not going to be disadvantaged by it next round. And if you don't want to make a funny joke out of your 1 that's fine too (most of my players don't take me up on that last bit tho).
- If you roll a crit keep in mind the "no severing limbs or disemboweling" guideline but it's like bloodied plus - feel free to knock yourself out with a description of how cool you look doing what you're doing.