How can I accommodate for last minute dropouts/additions?

Question

As most of you would likely know, a game is structured around the combined "level" of a party, with monsters having a "Challenge Rating" to match that. Additionally, other encounters (like a trap in a dungeon) might focus on how many individuals there are in a party, rather than their overall level, or sometimes you might want to make a session that is focussed entirely on a particular player that normally may not have much interaction in most other games (like an Orc Fighter in a party of Elf Wizards and Tiefling Sorcerers).

However, sometimes people just might not show; or even change their minds and cancel their plans to unexpectedly join your game. As a new GM, this is one of my biggest problems to try and manage.

For example:

• One game I planned for the party to hunt an Owlbear, but on the day, two players bailed. To manage this I was forced to botch a lot of rolls, as well as cut the creature's health just to make it a fair fight.
• Another was planned for two - the Rogue and the Druid (not particularly adept at combat, but crafty in other ways), so I made a low-level dungeon filled with lots of traps. However on the day, the Fighter showed unexpectedly. Needless to say that was a rather terrible botch job, having to constantly refer to the DMG and MM for additional enemies and such, to try and balance it for the Fighter, which made gameplay slow and rather stunted, and really killed the immersion.

In terms of fights, I know that this can be managed by creating "mobs", and just adding/removing them as necessary, but I don't want every single fight to just be a bunch of minions; especially if the boss is someone that the melee class can deal with in two hits, instead taking them several turns to cut through the waves of paper-thin enemies to get to them. That's just not overly fun. Alternatively, I'm not sure if cutting a Big Bad Guy's health in half just so the Rogue and Druid can deal with him, only to boost it back up to full the next time and have the Fighter/Barbarian struggle just as hard to defeat him.

Is there any tactics I should use for these types of situations, like plan for both situations (i.e. twice as much work), or just keep doing what I'm doing?

Answer 1

Play Dirty and Play Smart

One of the things that I discovered as a DM (and, admittedly, I'm not the best) is that D&D is heavily focused on advance preparation. Although there are definitely tools that can help you adapt on the fly to things that you won't necessarily find practical to use at the table.

One thing that I argue is to base the competence of any enemy commander/coordinator on the number of players present and adjust accordingly. This will mean that you adapt challenges somewhat in terms of number, but also that you accommodate other variables into your battlefield schema to ensure that combat can remain balanced even with unexpected player counts.

Some of this also depends on who your players are. If you wind up with a particularly bad balance of players (e.g. a solo Wizard with a disregard for combat spells), you might wind up not having a good way to balance an encounter.

One thing that I found with my unreliable group is that I had to steer away from big cinematic battles unless I was able to bring in an ally NPC or have the players cover for each others' characters. In some circles, that's controversial, in mine it was generally acknowledged that your character wouldn't die while in someone else's hands (though I rarely killed characters to begin with: my total PC death toll in several years of running games was around four) to make up for the fact that they might not be played totally responsibly.

Instead, I focused more on weak individual foes, the sort of creatures that can more easily be adapted on the fly: not only can you adjust the number of them, but relying on a basic knowledge of real tactics can make or break a fight involving a small number of individuals.

Number, Location, and Awareness

From a military science perspective, there are three main things that factor into how successful a character will be on the battlefield. The (in)famous story of Tucker's Kobolds illustrates this in a pretty simple manner from the AD&D days, and these principles remain to this day.

As such, all future examples for this answer will be given via kobolds. Enjoy.

Number

Play your enemies with a varying degree of cleverness based on how many PCs show up for the session. You don't need to drop from eight kobolds to two, even: just make sure that the kobolds never really outnumber the PCs, which ensures that they get a more or less even share in the combat rotation.

This will allow most PCs to fight a good number of enemies, but if you really want to make the players sweat toss six or eight enemies at them in one go. Even just a few enemy combatants getting turns that the PCs don't have anyone to match will quickly make up for the difference.

Likewise, if the PCs are in a place where they could have low-level NPCs of their own, a little ablative armor or light fire support can even the odds for a band of heroes caught without important combat-focused PCs.

The general advice I give when playing with numbers is that if you are going to add characters to balance a larger group you should keep them tiny. This stands even for a boss fight: if a new guy shows up on the day of the bossfight, so do a couple CR 1/4 inconveniences. Even a mighty combatant can be brought low with an unfortunate critical at the right moment (though D&D makes it somewhat difficult for that to happen at high levels).

Location

Give the players an advantageous location if they are underpowered or a disadvantageous location if they are too strong for the encounter. Consider their abilities: I made my DM unhappy with my archer ranger by playing a little too smart in combat and relying on cover all the time. Between heavy martial allies and a large boost to my AC, I was able to go a whole combat without taking a scratch.

Your NPCs can do that too: rely on terrain to slow or block PC movements, give Advantage or Disadvantage as needed, and redirect their motions.

If you are stuck with a couple PCs fighting a very tough boss, give them places to run to: temporary respites that allow them to apply restorative magic or take shots before the baddies can get into them (pillars work well for this when fighting 10x10 monsters: they can be brought down to allow access, but will allow characters an easy way out if they don't let themselves get cornered).

Likewise, if an extra PC shows up, the enemies are on the hospitable side of cover and they have no intention of leaving. Give them a little bit of a boost by leveling the playing field, rather than requiring you to consult the DMG or simply put extra figures on the field.

Awareness

Sometimes there's not a whole lot you can do about your players' awareness of the world around them. I've played with a group that can be blissfully unaware or keenly cunning depending on the weather, as well as groups that are either chronically lacking in tactical savvy or obsessive planners.

One of the best things to happen to the combat system are surprise rules. They can be a DM's nightmare, but even having something as simple as a hidden kobold fire a crossbow from a cranny can cause major pains for the party.

On the other hand, having the PCs know of all possible threats, their locations, and the full battlefield schema will provide them with an edge against most NPCs.

Consider adding more active elements to your scenes: give players a way to transform or exploit the terrain in a way their enemies aren't expecting (or vice versa). Throw in a minor trap that can slow a character down or take them out of combat for a round or two (which also helps with balancing numbers, if necessary) to provide an element of surprise that aids NPCs' efforts to stay alive without dooming the party to failure.

Answer 2

Is there any tactics I should use for these types of situations, like plan for both situations (i.e. twice as much work), or just keep doing what I'm doing?

There are a few things I do to try and mitigate issues like this, most of them are system-agnostic. Some depend on the game system in exactly how they're executed, but the idea is the same across systems.

• The first thing I do is I try to emphasize the importance of showing up regularly. I want everyone to show up every week if at all possible, and if they can't make it, call to let me know as soon as they can. I do the same myself. It's not perfect, but as long as everyone understands what's going on, it helps.

• I only play a particular game with at most 5 players (6 counting myself.) More than that becomes unmanageable very quickly, in my experience.

• No matter who shows or doesn't show, I always run the session. The fastest way to kill a campaign is not to play, after all. Don't take the easy way out and skip a session unless it's literally you and one other guy.

Specifically regarding how to balance encounters, this is my approach:

• I use CR as a very loose guideline. I learned several editions ago how easily it can be thrown off kilter due to party composition (with or without no-shows.)

• All the characters remain in the session, even if some players are not present. Characters whose player is not present are on auto-pilot, controlled by communal consensus of what "he would probably do." They still get attacked and might die, but they also still get XP and a share of the loot.

• If a given encounter is proving too difficult for the party, either due to last minute drop-outs or (more commonly) bad dice rolls, I fudge the enemy rolls to keep things going. Maybe the enemy routs after a particularly devastating round of combat, or something. I'm not going to TPK unless I have a really cool story idea for it, or the party is being REALLY stupid and asking for it. (I will comment of the stupidity of their plan before I TPK them, so they know this is likely to end badly.)

• If a given encounter is proving too easy, I throw some fuel on the fire. Reinforcements, sudden earthquakes/rock slides, whatever seems appropriate. Sometimes I'll just give them the easy win. Not every battle has to be epic, after all - in fact, having some not-so-epic battles helps to highlight the really epic ones when they happen.

Finally, vis-a-vis balancing encounters:

When building a dungeon/fortress/other location where Stuff Will Happen, I design it according to what's logical for the location and its inhabitants - NOT for the characters in the party. Sneaky monsters lay a lot of traps, swarmy monsters have a lot of numbers on their side. Big Dumb monsters just sit around and smash things. And so on. How the players choose to tackle a given location is up to them and what they have at their disposal. They'll find a way that suits their party.

In short, I don't (usually) go out of my to create scenarios where a given PC can "shine." Instead, I set up the scenario agnostic of the party and let the players figure out how to "shine" while exploring it. They come up with their own ideas, and I do my best to facilitate those ideas on the fly. I try not to shut down unexpected approaches to a problem, but to roll with them and have the enemy respond logically to what just happened.

Answer 3

After being burned a few times with doing a lot of prep work only to have the PCs take an unexpected path (bless their adventuresome hearts), I now wholeheartedly subscribe to the Lazy Dungeon Master method of preparation - light planning using loose templates, use lots of ad libbing, roll where the story takes you. It has led to much less stress in preparation and adds a level of discovery to the game for me as well. I highly recommend it (or the newer version, Return of the Lazy Dungeon Master) for this type of scenario and for general DM sanity.

One of my favorite quotes from the first edition of that book is:

No plan survives contact with the players. - Davena Oaks, The She DM

This is true, and one needs to be able to adapt quickly. While there are certainly times where I've had to play the bad cop and send the few players that showed up to their doom using the what I had planned (I hadn't expected a TPK, but they made some really poor choices and they refused to retreat), you have other options as well that should work for most gaming groups.

I offer these ideas for times when you just don't have it in you to scale an encounter at the last minute, or when what you had planned no longer makes sense with only part of the party present. I offer these up not as instead of the other answers, because those are great for times when you want to stick with your plan, but as alternative solutions to the problem when sticking to the original plan doesn't make sense for one reason or another.

Make use of the fantasy setting

In the last campaign I ran, a party of 7 PCs ended the previous session resting in a cavern filled with strange but harmless fungal and housing an alter that was mostly harmless and only mildly evil. For the follow up session I expected the players to finally head in the direction of the BBG and finish that leg of the campaign, so that's what I planned for in the weeks leading up to it. When game day arrived we were down to only 3 PCs. So, thinking quickly I used what was available to me and the fact that anything is possible in a fantasy setting:

• I grabbed a small one-shot from my library, one that was suitable for their levels and which I was already familiar with
• I explained that as they rested, the fungal spores and the presence awakened in the alter caused the 3 PCs to have a shared dream, drawing from their combined memories
• They started without any equipment, but otherwise had all their current abilities
• We played through the one shot normally otherwise, and they kept experience gained
• At the end, rather than keeping any physical items they had acquired, they each were able to take forward some arcane knowledge when they awoke

The players still got to roll play and roll dice, and I still got to DM, and it was something that fit the narrative.

Use flashbacks

Another time, a new player was about to join our group and all but 1 of the regular players had to cancel. I made use of the opportunity to introduce the new player to the world at large and build a connection between the new character and the old using a flashback session that drew on aspects of their backstories.

• The new player started with their character at level 1 (with the intent to level them up afterwards to a level closer to the other PCs)
• The existing player "dumbed down" their character by ignoring any special abilities granted to them after level 1 and role played a young version of themselves from before the main story line
• Since they both had backgrounds that described them as travelers, and since my regular players character had already been revealed to have been orphaned and raised by sailors, I put them both on a ship at sea, one as the young orphan and the other as a young traveler on his first voyage away from home.
• I turned to a low-level one-shot from my library for inspiration, took the main plot line and modified it to fit the situation - they were transporting some refugees to an uninhabited island to start a new settlement and would have to ensure they arrived safely
• At the end they both took their experience gained forward, and I used the flashback as a way to introduce the new character to the party at large as a former acquaintance still sailing with the same captain - and the two players now had an actual history to role play against.

Game on, just with a different game

You can use the time as an interlude between games and take a break as DM. Here's a few things my group has done in place of our normal campaign when we had too few players:

• Pull out that other RPG game you've been meaning to try, roll up characters and take them through the sample adventure to get a feel for the game. You might find things about it that are worth pulling into your regular session. (For instance, we recently used an interlude to explore The Black Hack and I'm planning on bringing their resource die and carry capacity rules into my next 5e campaign.)
• Grab a board game instead - You've got people at the table, so introduce them to your favorite game and take a break from the campaign for one session. My group liked this so much that we've starting to do this regularly every 3rd or 4th session, as well as between campaigns.
• You've probably got snacks and drinks already, so if there's too few of you and no one feels like playing a different game, just make it a social gathering (chances are you'll break out a game eventually - gamers gonna game after all)

Most gamers just want to game, regardless of what they play.

I've been on both sides of the DM screen, and it's disappointing to show up for a game session expecting to play only to have it cancelled because no one showed up. I know in my case I love any opportunity to play games whether role playing, card, or board, and since I've already planned on gaming I'd rather play something than nothing. I imagine your players are no different. And again, so as to avoid being flagged for off topic, I only offer this as an alternative to scaling the encounter - if you can scale the encounter and play as you planned, good on you! But if you can't or don't want to, you still have options to play something!