I've been frustrated for months with the NPCs in Out of the Abyss
I've been DMing Out of the Abyss for my group for months now, and the sheer number of followers has frustrated me for a substantial portion of that time. I actually had the very same goals that you do: keep the NPCs viable but in the background. I didn't want them to disappear during combat, but I also didn't want them overshadowing the players.
I found it impossible to balance the game around the number of NPCs that the party could have at any given time.
I tried changing health points around as you suggested, and I tried grouping up NPCs into distinct units based on the mass combat rules of in the DMG. I tried just having them fade into the background, upgrading their equipment over time, and I even tried giving each NPC a full turn in combat and letting the PCs run the NPCs in battle. And every option had the following problems:
- Combat was taking forever with so many creatures in initiative. Each NPC took time away from my players playing their own PCs. And if I ran all of the NPCs, I was frantically trying to keep the game moving and burned myself out within minutes just trying to keep up.
- NPCs aren't interesting. They don't have class features, don't really do anything all that special, are pretty weak, and it takes time away from you (the DM) playing cool monsters or the players playing their own PCs.
- They make fights a chore to balance. With so many extra bodies, and hit points and damage flooding the board, you either need to give enemy monsters supercharged hit points and damage, or you need to throw an army at the players to provide a challenge. Otherwise, the players can just steamroll an encounter super easy. That happened to me frequently and in every instance I felt like I had wasted valuable table time on a fight that was just plain too easy.
For all of these reasons, I switched to a support system instead of statting the NPCS and I suggest you do the same.
If you look on page 114 of OoTA there are certain benefits for completing tasks for the Svirfneblin. Some of those include benefits that the PCs can call on for free that represent Svirfneblin aid in battle without actually running any NPCs. I took this and built a system on based around it. Here is the gist of that system:
- NPCs do not roll initiative and have no physical representation in combat. They cannot be attacked or otherwise directly harmed by monsters.
- For every battle ready NPC companion in the party, the group gets one support point.
- A PC can use up to one support point on their turn to get some kind of benefit for free. The benefit represents the aid of an NPC
- Each benefit has a risk associated with it (low, medium, or high). Greater risk equals greater reward, but more chance of something going wrong.
- After a player uses a support point roll a d20 (no modifiers) with a target number based on the risk.
- If the d20 roll is below the target number something bad happens to the NPC, usually knocking them out until a short or long rest, or killing the NPC.
I found that this system was much better at addressing the number of NPCs in the party. It allows the players to spend more time doing cool stuff with their characters and it doesn't cause the massive combat bloat that running each individual NPC does. It also solves most of our issues. NPCs aren't as strong as the heroes, are purely supportive in nature, and stay in the background at all times to let the heroes shine. If you want, you could even give individual NPCs new benefits to show how they are developing with the players. For example, I myself gave an NPC a new benefit to add extra fire damage to a player's attack after the players gave that NPC a magic flaming sword.
Monsters in my system can't attack the NPCs though
Since each benefit comes with a risk, monsters don't directly attack NPCs in this system. Instead, when something bad happens to the NPC after providing their benefit, I simply narrate how their actions got them injured by one of the monsters, without actually using any of that monster's action economy. Still, I was perfectly willing to make that concession for all of the other benefits that this system provided.
If you want to see exactly the system I use, you can view it in this google doc