Balancing Encounters for Large Parties

[bokodasu]

How do you do it?

Right now I'm running a game for 7 L3 characters, and by the book I should be running encounters in the 5ish range, but it's taking closer to a 7 to challenge them, weighted towards more mobs rather than higher CRs. (They're also pretty experienced players.)

Now I'm going to be running a game for more like 10 L2 characters, much less experienced players, and I'm really not sure where I should be aiming to a) not overwhelm them and b) not give them a cakewalk either.

Do y'all have some general rules of thumb for handling this?

[gbprime]

Well you've got a mob of players, so you need a mob of monsters. Raw numbers or larger critters with DR 5/something are really the only tools you have to handle a party that large.

[Flickerdart]

Because there are so many people, they have an insurmountable action advantage against a single CR5. The obvious way would be indeed to use mobs (summoners or necromancers work wonders too), but that becomes a nightmare that makes turns take forever. There are other ways:

Bit fat sack of health: This guy might not be very good at dealing damage, but he's great at taking it. A full round of damage from the PCs will only take him down to about 2/3 of HP, so he's dangerous because he can outlast them. If he focuses fire on one guy at a time, he can force the PCs to retreat, one by one, before they break through his defenses.

Dangerous damage dealer: This guy isn't all that hearty, but sticking around within his range is almost certainly a death sentence. Again, PCs need to retreat and harass him from a distance (reducing their damage output) or try to keep him down (by tripping or stunning) instead of dealing damage. Either way, the effective DPR of the party drops.

Standing on a ledge: The enemy is not especially sturdy, nor very powerful, but before you can kill them, you have to get to them! Flying or gliding opponents are ideal for this role, but simply balancing on top of a greased column makes it difficult for the PCs to brutalize your troops. Anything where the PCs have to fulfill a certain condition before attacking (cross a raging river, dip their sword in the sacred fountain, catch the opponent before they can go Ethereal again) makes the encounter more difficult.

Divide and conquer: With so many people, the PCs might be tempted to send half down one passage and half down the other. Exploit this!

[Swooper]

I'm co-DMing in a game that has had up to about 13 characters at one point, but there's been some fluctuation in players so we're at about 10 left now. I don't have much to add that hasn't been said, other than we've found that giving monsters maximum HP helps them live long enough to act. Although, if 10 11th level gestalt characters manage focus fire on something, it just dies with a whimper, which is why multiple enemies are kind of a requirement for this to work.

One more thing, in case it's not obvious: Resist the temptation to use way over-CRed monsters. Even if the party as a whole can handle them, and it may seem like you need something like that to survive more than a round, they're liable to one-shot party members with their superior damage output.

[00dlez]

Flickerdart laid out the basics of what I would recommend, but just to expand on his points...

I often use "Mini-mobs" or another form of battlefield control to try and separate large parties. Not completely splitting the party, but putting enough distance between them in the encounter so that each of the groups is forced to take on a more reasonable number of opponents, then there is some sort of mini-boss that poses the real threat. Perhaps best outlined in an example.

tldnr: a wedge seperates the party into two "seperate" fights that themselves are easy, but a larger mobile threat forces PCs to operate sub-optimally and presents a greater challenge

Your party of 7, 3rd level heroes is trekking down a forest path when, uh oh, orc ambush. 7 orcs plus a "leader", Barb1/Rng2 Orc. This encounter is right about the CR 5 range and includes an ememy that can TWF and rage, putting out some serious damage to anyone wanting to get close, and can take a few hits too (see Flickerdart's points above.)

The orcs are all hidden, 4 to the north of the road, 3 to the south, and the leader is a ways down the path to the east.

The orcs open up with ranged weapons fire on the party, the leader remaining concealed. The party might split and rush the groups of weak enemies or simply return ranged fire. Enter the Leader.

Charging down the path, the leader can burst into the middle of the party, and being capable of some damage will scatter most squishy members (rogues, arc casters, bards, etc). The orcs can then close on these members in smaller groups and present more of a challenge.

[bokodasu]

Thanks! I'm still experimenting but your suggestions are helping. The relative experience of the parties is a huge factor - the bigger, less experienced group had a hard time with "properly" CR'd encounters, while the smaller, more experienced group is tearing through encounters 2 or 3 levels above what they should be for their party size & level.

Although at one point I had to laugh - part of the less-experienced group included two third grade girls, and they LOCKED DOWN those battlefields - someone would say "hey sweetie, do you want to cast Magic Missile?" and the 7-year-old would go, "no, I'm going to sleep anything that's an actual threat to us", while the 8-year-old used her entangling exhalation to tie down all the little mobs. When they had to go to bed, the grownups had some serious troubles.

[Lonely Tylenol]

As an aspiring schoolteacher and a DM of a group of 10 (down from 12, but may be going back up), let me tell you what my teachers told me:

Differentiation typically happens in one of four ways: acceleration (or pacing), novelty, depth, or complexity. It's importanr to make adjustments on one, maybe two levels, but don't go overboard with it. In D&D terms, these four methods of differentiation might be described as follows:

Acceleration: upping the CR of your encounter. Since this deals mainly with accelerating the content, you can use this as your basic slide-rule for straight-CR quantity or quality (CR level) of enemies.
Novelty: this usually consists of creating problems with distinct characteristics that require unique solutions. A good example of this might be adding the Greater Mummy template to an existing enemy; the template gives it a set of immunities and resistances that a melee-heavy party would need to play around, as well as special attacks and qualities that should be feared at low levels, but it also has a weakness (+50% damage from fire attacks), which can be exploited. Suddenly, the Sneak Attack-heavy Rogue is carrying Alchemist's Fire (if he knows what's good for him). This can either be your slide rule for special qualities of monsters, or for how "exotic" they are; a bizarre fighting style or something to that effect, which requires a unique workaround in order to be more effective.
Depth: creating bigger monsters. This is your slide rule for how beefy the monster you settle on is, usually either through HD advancement (of monsters) or class level advancement (of villains), but sometimes in the actual monster selection. I STRONGLY advise against relying heavily on this form of differentiation, as it's a killer at low levels (Dire Wolf vs. a large party of level 2 characters, where Dire Wolf has twice the hit bonus of anything else, and enough bonus damage to level most players on a decent roll), but is simply not enough at higher levels (when everyone can go nova, and action economy wins the day handily).
Complexity: the level of synergy in your encounter. This can involve either self-interaction ("how well does this monster's abilities and powers work with each other?") or cross-interaction ("how well does this monster's abilities and powers work with that monster's?"). This is your slide rule for how tactically effective your monster/s behave.

Differentiation can happen on any one of these levels, but it can happen with two of these levels together with greater effect. Consider these (each as a modification to a 2nd-to 3rd-level party fighting a 4th-level bad guy):
Acceleration + Complexity: a group of low-level warriors/fighters is led by their captain, who is a higher-level Bard. She casts Inspirational Boost in the surprise round, and then plays Inspire Courage--but produces a Dragonfire Inspiration effect instead! Now, the party is facing a group of low-level warriors who have +2d6 fire damage to their attacks, and are themselves a force to be reckoned with (glass cannons, sure, but difficult ones).
Novelty + Complexity: The party faces off against a 4th-level barbarian with a nasty temper... Only the barbarian happens to be a Goliath (mountain rage variant), and he is wielding a halberd of some sort! When he flies into a rage, he becomes visibly larger, and he holds the spear before him tenaciously! (From here, you could give him Combat Reflexes and Ferocity, refluffed to work with mountain rage, or Improved Trip, or EWP: Spiked Chain, or...)
Novelty + Depth: The character is indeed four class levels deep, but is in fact also a monstrous humanoid with RHD, which make him much tougher to handle: the party faces off against the Thri-Kreen Fighter 4 (or Warblade 4, whatever), master of the Four Swords style!

I'm sure you can think of other, better ways to differentiate. :smallbiggrin: