I am going to be implementing this into my MUD.
I have already implemented a full events based combat system in a previous MUD I coded. I will be tweaking this system for use in my new project. The way it worked is that various weapons had speeds and ranges and there were no more set "combat rounds" as you attacked as needed based on the speed of the weapon. I implemented multi-room combat, but that became a bit cumbersome. I will still use some multi-room combat features here (grenades, sniper rifles, launchers, bows/crossbows), but whereas before range was defined by rooms away from target, I will base it off a virtual distance in each room.
This way as a battle ensues in a room certain mobs/players can move away from melee to ranged distance or move into melee distance, or spear distance, etc... it will flow a lot better than trying to deal with multi-room ranged combat and will add some new depth and strategy to what is otherwise mundane spamming of skills/spells to kill. Add this with my FF7 materia-like skill system with skill/spell cooldowns and delayed effects you will have a pretty unique and rewarding mud combat system.
Nothing like seeing that player/mob start to reload their weapon and you rush into melee range, kick the weapon out of their hand, get behind them, stab them in the back, kick them over, put a steak into them so they are held down while while they bleed out and you move on to the next mob/player.