The dangers of a GM PC are huge! The moment they do too much it stops being a game. Once the GM is controlling both sides of the action in the game it's just a story. That means the other people in the group go from players to spectators and that isn't fun for anyone. As a GM, a lot of the excitement for me comes from not knowing what the players will come up with in any scenario. I do my best to anticipate them so they are challenged and enjoy the game, but the surprises are where the magic happens. A GM PC threatens that.
|An evocative image from the late Dave Trampier|
There are some terrible reasons to add a GM PC to the party. Some of the worst are things like, "guiding the story," or, "protecting the plot." If you want alpha readers for your novel it will go better if you are honest about it. Don't trick your players into doing that for you. "So the GM can play too," leads to some terrible wankery as well. Even if you have the best of intentions as the GM, you know what is coming, the deck is always stacked in your favour. It's not a challenge and it's definitely not much of a role playing game if the only variable is the dice.
Sometimes people will want a GM PC if a "critical" character class is missing from the party. This sort of thing often happens in D&D when no one wants to play a cleric. GM controlled clerics that are essentially just walking heal-bots ("OK, Kolbar casts Sanctuary and prepares to heal you guys") can always be replaced with a cache of healing potions. Solid play can solve a lot of these problems too. Hit points are a resource that are spent during the course of an adventure. Clerics are one way to extend that resource but solid strategy and magic items can do the same.
Fifth Edition D&D doesn't have the same niche problems. Between the backgrounds and the feats it's not hard to cover off all the skills and abilities that are useful during an adventure. For example, I play a Warlock in one game with the Healer feat who does an excellent job as the party healer even though we have a cleric, because the cleric player would rather cast battle spells and fight.
GM PCs are a good way to mess up a game. I don't like them and I don't use them. You can imagine my horror when I realized I needed one for a game I'm running.
I'm running a game for a couple of new players who didn't want to play with experienced players even though there are a tonne of amazing, supportive players who are great to new people in the hobby. It's only them and a party of two people is a problem. It's too small to challenge without risking a Total Party Kill in every encounter. One bad round is the end of them. Creative play can allow a party of two to dish out plenty of damage in an encounter but they still only have so many hit points. The players chose to make stealthy characters which helps but there are times where even the most clever players end up with their characters in a pitched battle. They need at least one more character there to divide the attention of the opposing forces.
I didn't want this added character to overshadow the PCs but I wanted a character that could draw fire and have the hit points to stay in the fight. My players also didn't create characters that could cast magic, which is pretty common for new players. That's why I also wanted the character to have some casting ability to help show the players the possibilities and get them comfortable with the magic rules.
I thought at first a fighter or paladin who went with a protector martial role would be good. Add in the Sage background, the Magic Initiate feat and we have a wizard's apprentice who took up arms after his/her master was killed in the field.
As cool as that sounded, I decided to go with a straight up wizard. I knew I wasn't introducing her until they got closer to their destination so I could start her at 2nd level with a School of Wizardry already established. I made her an Abjurer. The defensive magic and extra hit points make her extremely hard to kill. I decided that a Rock Gnome with their extra knowledge of magical devices would be handy because she could not only identify the function of magic items, but also their names and history which makes them more interesting. Even a +1 sword is special if it has a history. The Rock Gnomes also have a bonus to constitution which adds some more hit points.
I decided the only fair way to make the character is with the standard statistics (15, 14, 13, 12, 10 and 8) and standard hit points. I'm fairly lucky when it comes to rolling so this keeps the character in balance with the party, stat wise. I used the standard HP per level instead of rolling as well. It's high enough to hit my objective without giving them the wrong expectation for what a Wizard can be. Either of them could have made this character. Also, if one of the PCs dies the player might want to take over this character rather than roll up a new one so I need to keep it all fair and balanced.
In our second session it worked out well. The players had a forbidden book, the Malleus Deus from the Tales of the Scarecrow adventure they did in the first session. This forbidden item allows a wizard to cast a selection of cleric spells. After their new party member explained how dangerous it was to even know the location of this dreaded item they wrapped it up and locked it away at the Keep's vault. After some play they decided they trusted the wizard enough to let her transcribe a couple of spells into her book before locking it up again so she could cast Cure Light Wounds.
|Another one of Dave Trampier's images|
After railing against NPCs covering traditional party roles I have a little wizard who can take some serious damage, cast some useful wizard magic and healing spells. Still, she has no serious offensive spells, with only Sleep and Hold Person she is strictly support. No chance of overshadowing the rest of the party or becoming some kind of mobile weapon. So far, when in melee she casts Blade Ward or Shield to keep herself in the fight since she doesn't actually have an offensive cantrip.
We're several sessions in and the players like her, considering her a part of the team. They say she is useful without being in the way of anyone's fun. Jeff is more reckless than Megan so he tries to get the NPC to break standoffs with a third vote. The first time it happened I was surprised but should have realized that they would get the third member of the team to cast a vote. I'm not comfortable with that because I don't want to guide the party, but I do my best to keep my GM ideas out of it and rely of the character's back story and experience to make those calls.
Now that they are closing in on fourth level and have a third player starting next session I'm looking forward to transitioning the wizard out of the party and into a friendly NPC living at the Keep.