THERE IS ONLY SO MUCH THAT A Dungeon Master can do. When you are dealing with large groups of players, one has to know ones limit. Large groups take more time to go through, and require more enemies to challenge. If it takes a half an hour to complete your rounds, then it is time to add a Co-DM into the mix.


I honestly don’t believe in magic numbers, I think that Gygax stated that the magic number is 12 players to 1 DM, but I am nowhere nearly as talented as Gary was, I am comfortable with 8 players, anything above that and I’ll need a Co-DM. This number will no doubt, be different for everybody, and it shouldn’t be about the DM’s ego. This isn’t about the DM, this is about keeping a game smooth and fun for everybody.


Like I said, if it is taking over a half and hour for everybody to take their turn during a round, then it could be time to shorten up the groups. This is, after all, a game! And nobody wants to just sit there for too long waiting to attack. This is about player enjoyment, not the DM’s will to control everything. Everybody at the table should be equal, and be allowed to influence the group, PC’s aren’t henchmen and shouldn’t ever be treated as such.

Sometimes it is obvious, if the players decide that the best course of action is to split up into smaller groups, this is a big hint that it is taking to long to resolve conflicts, or that they want to break away because they aren’t having fun just going with the flow.

To many people talking over each other is a bad thing too. We are suppose to pump up the excitement, but if we can’t calm it down long enough to resolve combat fast enough for the players, it is time to get a co-DM.

We need to keep the players engaged in the game, we are shooting for total immersion, and to much free time leads to idle chatter which, of course, leads to us getting upset. . . well maybe not us, but me. I get upset. Grrrrr. That gives us another hint, players ignoring the DM. It isn’t usually because the game is boring, it is just that it is taking to long, and they feel that they can’t influence anything anyway.

We always need to watch everybody! There are loud players, and there are players that are quieter, not because they don’t have ideas, or don’t know what they are doing, but because they are just quieter people who don’t find competing for room to talk as something that they want to do.

Overall, the best advice that I can give you is to be mindful. Pay attention and don’t be afraid to ask for help.

If you are a new DM, you shouldn’t go above or below 4 players. From my experience, this is the perfect number, anything to low and you’ll probably kill them all, and anything over that they may not be challenged enough and you’ll overcompensate and end up killing them too. You should definitely use a co-DM when first learning the ropes.


There are different degrees of co-DMing. The job is simply to take off some of the duties of the Dungeon Master. The first degree is simple bookwork. Most of our work should take place during the prep stage, but nobody is perfect, and nobody can anticipate all of the crazy stuff that player characters think up. The first degree of co-DMing is the simplest, simply looking up facts. Don’t be afraid to toss a player a book and tell them to look it up while you continue working with the other players. This can be a fact that is only useful to them, or even a fact that you yourself need to know.

The second degree requires more trust, as you’ll be giving them information. They will be running combat for half of the table. Essentially, the party will be cut off from one another and the CO will be working semi-independently from you. If he has a question, you’ll need to be ready to answer it quickly, and you will need to prep this for him well before you can let him have at it. The prep may just be a list of monster stats, or it can be a map and a magic item which a monster is using.

The third degree requires the most trust, and the most forethought. If the party is too big, then they may need to be split up permanently at a completely different table. This party will be in the same dungeon, but split, either by choice or by a magical device that teleports them away from you. This co-DM will have the same amount of authority as you, and needs to know everything about the dungeon, or run a completely different adventure depending on how big the group is and if they are regular players or not. This essentially is running a completely different game. This could be just for a specific amount of time which was preplanned by the characters where they decide to split up and meet back here when they all know more. Or, like I said, it could turn into a completely different game for awhile before the party meets back up with one another. It doesn’t take much of an imagination to see the potential ramifications of this happening, but it does happen.


For the first degree, we are just throwing them a book. Anybody can do this, and it doesn’t require any skill what-so-ever. If it is to answer a question put forth by a player, then make them look it up themselves and read the answer aloud. If it is something for you, then you need to chose somebody different, but who?

If an experienced DM is playing the table, then they probably already know the answer, or can look it up the fastest. If you are more minded to give back to the hobby by teaching others, a player who is playing a wizard is probably your best bet. It takes a lot of experience and reading to play an effective wizard. Of course if they are just trying the class out for the first time, then you’ll want to leave them alone from being a runner, but if they are experienced, then they probably know the books just as well as you do.

We will be looking for somebody who isn’t currently engaged at the time. If it is during combat, warriors are usually out, but some characters are best left hanging out in the background and have a bit more time on their hands. If it is just a quick fact, then ask somebody with a ranged weapon to look it up for you.

This is also a test! Watch your quiet people, because sometimes, it is the quiet people who make the best Dungeon Masters, and you can possibly keep them engaged with a game by allowing them to Co-DM. If they are just shy, then it will force them to talk with their split party.

For the second degree of co-DMing, we’ll need an experienced player preferably with some experience DMing, but that really isn’t necessary. Running combat is a skill that is best learned in a trial by fire situation. Perhaps their character bit the dust and died, or you believe that they are capable of running their character on a temp NPC status. Of course the above is still true, we don’t want a warrior who is always on the front-line to actually have to run the combat, but somebody who is more in the background. You should also be very clear as to what your expectations are! Let them know that their character isn’t allowed to come up with brilliant plans, and he isn’t allowed to use the information that he is about to get for his character. You are still the DM and if he ends up with anything that isn’t on the info that you gave him, then it didn’t happen. Your authority is still the final word in any matter, but we ourselves will need to be fair about all judgment calls in regards to the co-DM.

For the third degree, of course the player has to lose his status as a character altogether. It simply isn’t possible to play a character and referee fairly at the same time. Depending on the situation, the co-DM can have total authority, or, if it is in the same dungeon, semi-equal authority with exceptions made for continuity reasons. This is actually one of the best ways to learn the art of DMing, because an experienced DM is right there for quick questions, and all of your notes are laid out for you. If the two parties will be playing in the exact same dungeon, then a meeting should take place between the two DMs before and after each session to compare notes for continuity reasons, for example destroyed objects, dead NPC’s and monsters, fallen comrades, treasure taken, etc. If it is two different dungeons, then continuity won’t be a problem, but the new DM might want to touch base and just chat with the experienced one.

To reiterate: A candidate for a co-DM is someone who isn’t always engaged in active combat such as a wizard or a thief, somebody who is quiet and doesn’t actively lead the party on a regular basis, someone who is disrupting the game and can be given more responsibilities to keep them more engaged, or somebody who has lost their character to death and doesn’t want to spend the game time writing up a new one.

Good traits of a co-DM include the ability to separate himself from his character, and doesn’t mind the temporary NPC status, and has the ability to play dumb when the time comes.


This isn’t something that can just be done on the whim, you have to have the forethought to know when, and who you can lean on for support. Before leaning on a co-DM talk to him or her and make sure that this is something that they’d be interested in doing to begin with. Most people will at least try it, but if you can tell that they absolutely don’t want to, then don’t push it.

If they are first-timers, then you’ll need to make really good notes, and teach your CO how to read them. I know that I keep my note-taking pretty consistent as far as creatures are concerned, however I leave some stuff out which I don’t think that I’ll need. If I were to require a CO, then I would make my creature notes complete, and include the page numbers in the Monster Manual incase they have to look something up. If I am going to have them run a specific rule-set, then I’ll also need to write were the relevant information is at.

They won’t be prepping the dungeon themselves, but they should have all of the related subjects reviewed prior to running the combat or scenario. Of course if they are DMing their own parties at a separate table, then they will need to do some prep. It is easier now for a DM to prepare easy to read, professional looking, module-like, quality dungeons with almost no extra work. Naturally, if you are coming up with this stuff as you go, then a CO is impossible. If you are using a module, then go through the thing with them and tell them about any changes that you are making, and listen to their suggestions as well. The third degree is the hardest to pull off, but if your communication skills with your CO is good, then it can turn into something really special.


Now this list is nowhere near complete, or a end-all be-all guide. It isn’t even something that I would suggest doing on a regular basis, but if the right situation presents itself, then by all means, resort to co-DM’s!

Phase 1

Chances are, you do this all of the time. When a player tracks a henchman NPC he is essentially co-DMing. You still have the final say-so involving all decisions in regards to the henchman’s safety and property, but you trust much of the work to the player who is responsible for him.

Looking up magic items and spells are a pain in the butt. As a DM, it is hard enough keeping track of your own spell users, don’t be ashamed to ask a player exactly what a spell does, or if he finds a magic item, toss him your DMG or whatever book the thing is from, and have him either review it aloud, or write it down for himself.

A party needs responsible people. There are two roles within the party which are important, the first is the leader. This person will be responsible for rolling the groups initiative, as well as in times where everybody at the table falls victim to mass-hysteria and the DM needs to find out what is going on. The leader will have the final say-so in regards to any group decision making. It is his job to calm down the table, and lead the party to reach their goals. The leadership can change, and often does, at any time and from game to game. It is this person who major NPC’s will want to deal with, and talk directly to.

Another important part of the group is the Quartermaster. While the leadership of an adventuring party can change frequently, the Quartermaster should always stay the same. It will be the Quartermaster who is in charge of buying supplies and keeping tabs on everything that the party uses, typically this will be done with a WIS check, thus the Quartermaster will be the wisest party-member.

Phase 2

Now since there will be two Dungeon Masters at one table, folks will have to keep calm. This is typically done during large combat scenarios and require the party splitting up temporarily but staying in the same general area. The DM is paying attention to what they are doing on the other side of the table, but running his NPC list independently.

Three armies are engaged in warfare, two enemy armies, and the PCs who must split up and fight on two different fronts at once or be destroyed.

Enemy has the party surrounded.

Part of the PC party decides to flee, or give chase to fleeing monsters for a short distance but without leaving the battlefield entirely.

A PC wants to split from the party to accomplish a goal or objective with the aid of the co-DM’s character. This can be used in the city where a thief wants to sneak into an NPC’s house and steal information or clues, or even for a wizard who wishes to sneak away and find a better place to fight from at a distance.

Anytime a party-member wants to split to accomplish a goal that can quickly end a conflict, but requires a majority of the party to keep fighting as a distraction until the party-member and his support member (read co-DM’s character) can complete the objective.

Phase 3

Since there is so many different degrees of this, phase, we’ll break it down into two different groups. The first degree is Joined, meaning that they will not leave the general area too far and stay in the same continuity with plans to rejoin the main party later; and the Second degree is Divorced, meaning that they have split off permanently in either the same continuity or in a completely different one.

1st Degree

This second party can be as big as what the co-DM is comfortable with, or as small as just the CO and PC playing 1-on-1. This differs from the Phase 2 because this time the party will be leaving the area entirely.

For instance, a large group decides to split up inside of the city limits and complete two different objectives independently of the other. This may be two separate villages or locations entirely! But they do have plans of meeting up again at a specific location once they are finished.

The party has been split by a villain or a device to different areas of a megadungeon, or the party has decided to split up for the duration of the dungeon. This will require continuity and the party may meet each other again at some point in the dungeon.

Members of one race or class, such as elves or thieves, want to explore without losing their bonuses for moving silently and can complete a different objective inside of the same dungeon as their peers.

2nd Degree

There is just to many players and somebody wants to learn how to DM, so he runs the same dungeon as you but not in the same continuity.

There is enough temporary players to form their own separate party and it sounds like fun to have them compete for items and treasure in the same dungeon as you, and in the same continuity.

So many people didn’t show up one week that they were simply left behind by those that did. They will remain in the same continuity but be severely behind and have to play catch-up. Naturally, you yourself could do this one on an off night if members of that party had legitimate reasons for not attending or have no interest in leaving the game.

The party collapses because of lack of cohesion and dissension among the ranks, or they start out as just scouting a separate hall, but can’t find their way back and are left behind. This can either be in the same continuity or not depending on the skill of the co-DM.

Sometimes a party can become unbalanced, and two games need to be run in different ways to help those that are behind in levels to catch up so that they can survive. This happens for a variety of reasons, and a co-DM can either help XP wanting players get the XP they need, or just run the fun time-passing, low XP gaining game with folks who are their to simply play. Whatever you or they agree on! For stuff like that, a higher level NPC really should accompany them anyway, so why not have the co-DM take his PC in there with them, just to soften the badguys up some and aid them if they need it. It is easier for smaller groups to gain XP then it is for larger groups. This should also be a factor in if you need a co-DM that night or not, but it really does depend on the situation. I know that I have people coming in and out of my games all of the time, stuff like that happens! We all have families and work so it isn’t a big deal, but I still need to keep things in continuity. God forbid that everybody shows up one night!


Being chosen as a CO is a big deal. It means that your DM trust you with his baby, and finds you to be a responsible hobbyist. We don’t want to let him down. Below is a quick list of some of the traits that will convince him that he didn’t make a mistake in choosing you.

  • No new house rules without his okaying them.

This is a big one, and can anger players and your DM alike. Say if you use a “Fumble on 1” rule and the DM doesn’t, your players are going to get mad when you come out of left field and make a call which is inconsistent to how the game was ran before.

  • Be creative, but don’t add anything major.

There is a balance of power which the DM is observing, it is this balance of power that keeps things like “+22 Vorpal Fire Swords” out of his dungeon, don’t add them yourselves because you think that it would be cool. Observe the balance of the game and limit yourself to the things which the DM gave you to give out. If you feel that the party is underpowered, go ahead and talk to him about it and find out why he has it that way before just giving out magic items like they are tic-tacs. He may agree with you and let you add some things on your list, but for drastic changes like that seek his approval. Limit your creativity to describing what the players are seeing and feeling.

  • Take good notes yourself.

If we add a secret door, this is fine, but jot down a note and get it to the DM as soon as possible. Being a good communicator is part of DMing, you don’t need to be loud to be a good communicator, just good at telling him the things that were changed because of your own mistakes, or because of the actions of the players under you. They needn’t be advanced, but they should be good enough that he can read them and find the change immediately.

  • Take initiative.

Don’t bug him over little things every five minutes. Minor changes and major decisions are completely up to you in regards to refereeing the player characters. These people are experts at catching the DM off guard, and they will do the same thing to you, just go with the flow and try your best to make sense of what is happening with what the DM gave you. Keep the core information, but how you interpret it is up to you.

  • Separate yourself from your character.

If you are playing a character at the same time that you are co-DMing, keep him as an NPC, but remember that he is now an NPC. It isn’t any fun for an NPC to take a game over, he should just be there to assist, and hang out in the background. Do not give any ideas, or do anything else of your own initiative. Only perform a skill if you are asked to, and let all of the playing up to the players themselves. If your DM did give you any secrets, it is your duty to remember that your character is not aware of them and you cannot use this information once you get back to playing. This includes maps, items that went unfound, weaknesses within the ranks of the enemy, anything which you learned from your time co-DMing, this can be hard but, after all, if the DM didn’t think that you couldn’t do it, then he wouldn’t have picked you to begin with.


  • Be understanding.

There is never an excuse to be a jerk. Never yell at the Co or belittle his ideas. He isn’t a stooge, he should be a partner. If he makes a mistake then just go with it. We all do it and you know it. As long as he doesn’t abuse his new-found powers then he’s doing a good job.

  • Give him just enough to get him by.

Leave him enough leeway that he can use creativity, but within a structured setting. Give him the toolbox with everything that he needs and just let everything that you didn’t define go. Have faith and let it go. The more that you define, the greater the chances of him screwing it up are.

  • Pay attention but don’t dominate

The reason for doing this is so that you don’t have to do it yourself, just let it go you control-freak you. Repair damage later, if in fact that it was damage.

  • Keep him up to date.

Communication is a two way road, and you are the teacher or the most responsible one because this is your story. He can learn more about what you want from the notes by writing them well yourself.

  • Don’t leave out important details.

Have faith in him that he won’t use secrets against you. For the right character, this can improve his game once he rejoins. If you keep secrets that are important to the scenarios that you gave him then he is doomed to failure because he can’t fully grasp the motives of the monsters which he is running. He should know exactly what they know incase he gets interrogated by the PCs.


This solution is not perfect for all groups, in all degrees. Sometimes players play under a specific DM for a reason and they don’t want to change. Other times a DM is simply not capable of giving up a single ounce of power, or has a personality which makes teaching others impossible. Though this, I find to be in bad form, I’d rather them NOT teach others rather then chasing folks away from the hobby completely.

On a brighter note: This can lead to some extra work for a Dungeon Master, but in the long run, it can relieve you from duties when you really feel like playing! It also gives back to the hobby, which is just as important. DMing is a hard skill to master when you don’t have a good teacher.

A few of the scenarios that I laid out actually sound like a ton of fun! I mean, imagine two independent parties looting the same dungeon. There is just something about that that really gets my Geek-Gland dancing and spewing oozy-gooey nerd juice all over my innards.

Art: "Companions of the Lance" by Larry Elmore 1988


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