Modifying "The Night Before Wintermas" for a larger party and longer duration

Question

This will be my first time DMing, so I am not sure how to do this yet. The adventure is written for 5 level 5 PC's, but we will have 8 PC's in our group that night. How do I modify the encounters so they are not too easy? I would upload the short adventure so you can read through it, but I am not sure how.

The "monsters" are things like animated snowmen 41 HP, 12 AC and Frosty 78 HP, 12 AC, "Paindeer" 60 HP, 13 AC, and then a possessed Santa 134 HP, 15 AC that drops when his HP gets to a certain level and an evil avatar comes out of him 116 HP, 16 AC.

I know this is a one shot and will be finished the night we play it, but I need it to last at least 4 hours, and don't want them to blow through it in an hour and a half. I also don't want to modify it in a way that will result in a TPK early on in the game.

Any one have any suggestions? I know I will probably learn a lot that night as this will be my first time to run a game, but I want to make it as fun as possible for the group. I have also built some terrain pieces for the encounters.

Answer 1

The simplest solution, and one that I believe hews fairly close to the official answer, is to increase the number of enemies by a similar ratio. In your case, add half again as many. Worth noting: you're a first-time DM, the players won't have worked with their characters before, and for most groups, having things be a bit too easy is more fun than having them be too hard. Also, you should expect to lose at least some time to people not being entirely sure how to do things, especially if you and/or any of your friends are relatively new to D&D 5e in general. Thus, erring on the side of making it a bit too easy is probably better than erring on the side of making it a bit too hard. This is especially true if the person making the characters is relatively new at this.

Answer 2

The two quickest ways are:

1. Add more monsters
2. Make better monsters

If you add more monsters, they do not have to be the same. You don't need to have more snowmen. You can add in ice lizards, or a frost elemental. Makes the encounter less of a "Rinse. Lather. Repeat." situation. I prefer to save the horde idea using lesser creatures.

"Oh look, it's a lone kobold. No.. It's two.. three... seven... Um, guys..."

You can also make "better" monsters. Same number, but with different qualities. If you have a surplus of magic casters, make a few that can counter-spell. There was some magic in that old hat they found! Or perhaps a few grab sleds to use as shields to take on all the extra fighters? Too may thieves? Some snowmen have coal/eyes literally in the back of their head preventing sneak attacks. Some paindeer can absorb and throw back lightning spells. One has a nose that casts Prismatic Spray. I don't have the module so this may already be a thing.

The key is to add a little diversity so that it's not a case of the party having three more attacks per round. Make them be creative in how they use extra resources.

Answer 3

Short Answer: Add more hp to the monsters in addition to addition to adding more monsters

Adding more monsters is the way to scale with more players. More monsters add more damage per round thrown at the players. Since you have more players and more hp, they can handle this balance.

A great way to measure this is to look at the current encounter situation. How many monsters are standard and what are their average damage per round, with the assumption that they would all hit every round. Then compare this to the number of players the encounter is supposed to handle. Use this ratio when adding monsters so that you can balance for a group size you know you're going to have.

Adding hit points to the monsters in an encounter is a way to add rounds in an encounter, while maintaining the amount of damage that is thrown at the players.

The best way to measure this is to now look at your party, or try to plan for them. Look at about how much damage they average in a round, and then add hit points to handle the monsters surviving extra rounds of this damage output

As a new DM, you're already dealing with the management of the encounter, and adding the extra effort of managing a larger than average party. In later sessions when you are more comfortable with that management, then you can feel free to diversify your monsters and all of their different stat blocks.

Answer 4

For group enemies, add more monsters

half-again-as-many monsters here is a good rule of thumb, since you have half-again-as-many players, as other answers have already pointed out. You also can vary the sort of monsters you add and occasionally add hp or abilities to an existing monster or monsters to help with the blandness of simply adding more identical creatures, as other answers mention.

For small traps, add more of them elsewhere

Traps like "covered 10' pit with sharpened candy canes, 1d6 falling+1d6 piercing, Wis(perception) DC 20 to notice" can just have an equal number thrown around the module as extras-- after running into them the first time the players will be on the lookout and are less likely to be caught unawares by repeats, but combat or other eventualities might force them into one nonetheless.

For big traps, adjust for the additional players manually

A room with 5 chairs that all need to be sat in to open a door to some treasure, but then the chairs bind the PCs, obviously needs 8 chairs now instead of 5. Similarly, if the metal grating that falls, trapping the PCs in the path of onrushing molasses, weighs enough that 4 strong PCs working together should be just able to lift it, then now it should be heavy enough that 5 or 6 PCs are needed. If Jack Frost asks the players a riddle in exchange for not eating their souls, no adjustment at all is necessary.

For solo monsters, give them legendary and/or lair actions

legendary and lair actions help solo monsters keep up with players in the action economy. While typically only cool, high-level boss monsters get legendary actions, actually all of them should and the system works great. Make up some minor off-turn actions for the solo monsters to take (typically including at least one minor attack against an adjacent opponent, one way of struggling against bad positioning, and one cool "Behold my true power!" ability that takes all of their actions), reusing parts of their regular actions where applicable, and give 'em 3 legendary actions per round. If they already had legendary actions, give them an extra one each round or add a lair action. I've found legendary actions much more satisfying that lair actions for bosses, but minor solo enemies could probably make better use of lair actions instead, so they don't detract from the awesomeness of the boss.

For noncombat, nontrap challenges, do nothing

Stuff like opportunities to use Herb Lore or an encounter with friendly gingerbread men that provide information on the local area don't need to be adjusted. It's true that this makes the larger party much more likely to get all the things and make all the optional checks and gather all the people-based information, but adding more of these checks takes much too much time (NPC dialogue in a group of 8 is at a premium already, and Herb Lore checks etc only involves characters that have the relevant skills) and making the checks harder means its likely that one of the players will fail at the thing they specialized in the only time that specialty comes up, which is no fun. Leaving it as-is lets people potentially get a little bit of premium spotlight time without spending too much time on individual player activities.

Answer 5

I admit that I'm more familiar with Pathfinder CR, though from my personal experience, it would honestly depend on how many people are in the party. I have sat in on various campaigns where GMs threw 2 kobolds at a party of 5 because the CR and APL were equal, and no other reason. I find that the CR you should shoot for is equal to the APL+the number of players. For instance, as far as Pathfinder goes anyway, fighting 6 bandits (CR 3) would be just as difficult for party of 3 Lvl1 characters as it would be for a Lvl3 character. In fact, since the one shot was designed for 5 Lvl5s, the actual CR of certain encounters might be 10 instead of 5.

My suggestion is the following:

increase/decrease the CR by adding/subtracting creatures according to the party size AND level

if there are traps, fudge them slightly to be challenging for the Lvl8s, while doable for the lower-level partymembers that you may or may not have mentioned

good luck and happy holidays

Answer 6

More monsters, more powerful boss.

Add in some extra baddies, or some extra waves. Take note of the extra spell slots available to determine which you would prefer. More of the same might be boring, so just grab a stat block from the mm and edit it. Maybe a bunch of misfit toys or something.

Most importantly, make sure the final boss feels like a final boss. Maybe give him a henchman or two. Evil Christmas elves that hurl exploding presents? Or up his hp by about 30 and his ac by 1 to make it not feel like the fight was too easy.