How do you alter encounter difficulty in regards to decreased party size?

Question

Encounters are usually written in advance and balanced against the makeup and the abilities of the party. Sometimes though the party makeup when writing such an encounter in advance and when actully at the table differs: either because a player could not show up and called in without the DM being able to re-write the encounter, or because of character death.

Now, most parties won't retreat when facing sudden character death and keep on with the (n-1) of them. But the encounters will be scaled to a full-sized party, and as such be more difficult. When one player is down the encounter could still be managed, but when there are significant losses (four or less players taking on a six player encounter) things can go bad fast. In some cases it might be logical for the players to retreat, raise the dead/get new party members and plan for a second attack, but this is not always the best idea because otherwise Bad Things may happen. So how do you, if at all, retool your encounters?

Of course, encounters consisting of gangs of goons could be cut down to match the party, and you might be able to de-level a big monster a bit or replace it with something else. But I'm not too fond of this idea because when you have to fight plot-important enemies such as a group of six villains who are the dark equivalents of the party having some not be there for the big fight is odd, and it would be strange if the vampire villain Count Bloodsuckula got his hands on the Artifact of Significant Badassery and uses its magic to become more powerful... only to be at a lower level than the last time the party faced him because the Barbarian and the Druid got munched on by Wights a few rooms back.

A solution would be to somehow introduce new characters the players build in advance or build them as temporary NPCs to join the party... but if I go through that effort I might as well come up with retooled encounters in advance. So how do you handle the retooling of your encounters?

Answer 1

One super hacky and relatively system independent fix would be to figure out what that character would have done (on average) in the fight and make that already have happened or have the ability to happen due to terrain/environment/NPCs/...etc. Something possibly triggerable by the PCs but not directly from their characters.

For example, if the major damage dealer went down and you estimate that they were roughly responsible for half the group's damage, see if you can figure out a way for something to happen that would cause the monster to start with that amount, or some kind of effect they can trigger (relatively easily but with a bit of cleverness so it doesn't feel like an obvious handicap) that will eat about that amount of damage either all at once or over the course of the battle.

This of course will not adjust for the action economy which is rather critical in many games, but if you add a little slop or find a way for remaining characters to get a little extra bang for their metaphorical buck then in theory it should work itself out. Worst case scenario you can always give them some sort of out so they can wait to face this kind of threat until they are ready for it again; exploring failure can be a fun RPG experience, especially if it gives them the chance to turn it around later and fix what went wrong.

If for whatever reason the person in question was not particularly stand out in any area, then you can still use this strategy. Assume they did 1/[old party size] of the damage and then apply the adjustments listed above. The biggest thing here is going to be the lowered damage output, the less allied actions per round, and the fact that there's one less person around to take damage and debilitating effects. Because of these factors you're going to want to, beyond the additional damage and such to the opponents either starting or during the battle, make sure that you both spread damage around and focus effects that shut down players or require actions of maintenance to get out of so you don't debilitate so much of the group they don't have enough actions to effectively get out of it.

On a side thematic sense don't forget that an enemy who's not at 100% due to dealing with something else can still come off as pretty badass (and not seem nerfed) if they are still a big threat after going through more of a ringer than your group did.

Answer 2

"Otherwise bad things might happen" is really where the game is getting the most fun for a lot of people. I very much advocate letting those bad things happening and then have the players deal with the consequences later once they are back to full strength. This makes the game as a whole generally much more rewarding for the players, as the understand that they will only win if they work hard for it. If the game just gets easier when they make mistakes and they still win the adventure in just the same way as if they had played very well, there is very little sense of accomplishment. Then the players are just spectators to a story that has already been fully written and they don't really have a chance to change the game world with their actions.

Bad things happening because the players are not able to do everything as planned is really not a bad thing for the campaign. If they lose, they don't have to be all killed. When a fight is impossible to win, the players may either get the idea to flee themselves, or their enemies could demand that they surrender and throw them into some kind of prison for later. Then the players have to figure out a way to get out of prison and to deal with the time they lost in the meantime.