D&D 5E Balance Concern in Elder Brain/Ulitharid encounter(s)

[Trit One-Ear]

Hey all,

I'm finally putting together the details for a big boss fight as the end to a murder mystery my players have been sorting out. Part of the "twist" is that a tiny group of mind flayers are responsible for murder as well as several other mysterious happenings in the local town. The heroes will venture into the caverns below the town and find the small surviving mind flayers from a colony mostly destroyed by githyanki attackers.

My part of 6 is all 11th level, and are heavy on magic users: Eloquence Bard (control focus), Tempest Cleric (tank/healer/blaster swing), Wild Magic Sorcerer (blaster), Hexblade Warlock (striker), Scribe Wizard (controler) ... and their friendly Ancestral Guardian Barbarian (tank/striker). So far, they've stomped through most "Deadly" encounters I've thrown at them, with the occasional KO but no deaths. I'm still not super confident in my ability to gauge the difficulty of encounters, despite years of 5e play, so I figured I'd ask for some input.

I'm learning to stop pulling my punches (a bad DM habit I picked up from when we first started playing), so I'm thinking "Hell with it, throw an Elder Brain at them." It fits in narratively (with a little tweaking) and will certainly be a memorable encounter. But looking through the stats... I'm starting to wonder if this is going to be too deadly a fight.

I'm looking at designing either 1 huge and difficult encounter, with both the Elder Brain, the Ulitharid, and their small group of thralls/normal mind flayers, or splitting it into 2 encounters, with the Ulitharid confronting the party before they get to the Elder Brain.

The Ulitharid has been kidnapping some of the local populace, including some of the Leonin Royal Guards and Gnomish resistance fighters, so these aren't going to be pushover thralls. CR 5ish Paladins and Rouge types. There are also a small number of normal mind flayers present.
I'm also considering including Swarms of Cranium Rats, a few lowly Quaggoths for minion fodder, and Intellect Devourers to burst out of the powerful thralls when those are defeated.
These minions will be split between the two encounters if I decide to go that route.

My main concern is... the Elder Brain looks super nasty. High amounts of psychic damage (screwing over the Barbarian), breaking spell Concentration for my various casters, Intelligence Saving Throws (difficult for all but the Wizard)... not to mention Magic Resistance and Lair Actions.

Am I over thinking this? I'm staying within my daily XP limits, but the Elder Brain is only 1 CR below XGTE's suggested Solo Monster rating, and it's definitely not going to be without some minions. I know encounter building is more an art than a science, but I'm just looking for some feedback.

Thanks for any and all input!

Trit

 

[UngainlyTitan]

I suspect it is not tough enough. I have found the advise contained here very helpful. The official advise is overly cautious and you have a big tough party.

 

[Stalker0]

My party of 6 has fought an elder brain before, and like yours typical stomp high difficulty encounters.

The brain was no big deal for my 10th level party (and I gave it a special container that gave it big cover as well). Don't forget that many of the elder brain's powers requires a psychic link, which generally only happens if the party get incapacitated (stun from a mind blast is the easiest way).

The brain is a really good villain from a far, but once my party got in a room with it they just took it to town.

 

[Quickleaf]

Fun scenario, Trit! Here are my thoughts as I'm reading through...

Encounter Building: I'd consider general flow of the fight & what you expect to change during combat (e.g. reinforcements, thralls being freed, ulitharid vs elder brain tension, defensive perimeter, intellect devourers springing from thralls), but I'd start with the elder brain, ulitharid, and 4 mind flayers as the heart of your battle and build around them. Then sprinkle on other lesser foes as needed/desired.

Creature Sense & defensive prep: Elder brain can sense creatures up to 5 miles away, so unless the players are taking special measures or have some plot mcguffin, the elder brain knows the party coming and should pursue additional recon (e.g. cranium rats) and make some defensive preparations.

Sitting Duck issue / encounter distance: In the face of artillery/blaster superiority – which your party definitely has in spades – the elder brain could be a bit of a sitting duck. Definitely I'd set up the terrain/room so that the furthest a creature could be from the elder brain & still have line of sight to it would be 60 feet. In fact, since it's only reliably dangerous at 30 feet, I'd consider some kind of cover (or even a magical field or mucilaginous sphere) surrounding it at 30 feet away, so if you're outside of that area it's harder to affect the elder brain, but once inside (and thus within range of its tentacles) it's a normal attack/save.

Cavernous terrain: I would look for an opportunity to showcase what is unique about the underground terrain in this particular area, and ideally make it advantage the illithids (at least initially). Something like "scream stone" formations which if it would take psychic damage emits a high-pitched magic negating/draining pulse.

Exploitable echoes of the githyanki fight: Some way for Channel Divinity or Spell Slot expenditure to activate astral energies of a device, trap, or portal left in the wake of the githyanki assault. Ideally in a risky position. Something which, if the players think to use it, take the risk, and spend the action in combat, could give them the upper hand (e.g. teleporting past illithid defenses OR escaping the illithid's stun-locking potential).

Illithids vs. Tanks (Monster Tactics): The regular illithids should prioritize dominating the barbarian, and using Tentacle attacks vs. Cleric (or really anyone except the Bard and Wizard). A 19 Intelligence foe should be able to deduce this strategy within the first round of combat, or perhaps even before combat if they've been apprised by the elder brain of the party's composition. The battle with the regular illithids will be the players balancing using their action economy to keep distance between themselves and the illithids (as illithids are scariest in melee), vs. using their action economy to target the elder brain and/or ulitharid.

Thralls... use with caution ...possibly tie to Legendary Resistances: Since your party was just dealing with a murder scenario, IF you want to use thralls, I'd suggest building in some way to free them (or at least the most sympathetic of them) from the illithid control. Of course, players may want to turn their new-found allies against the illithids, so you might want to foreshadow a way to break the thrall-dom but temporarily incapacitating the victims.

I'd also consider giving its Legendary Resistances a concrete embodiment in victims trapped within pools of green gel that can be drained by the elder brain's tendrils. This creates a little dilemma / mini-game in which players can either try to free or kill these victims to deny the elder brain Legendary Resistances. Just a thought. This approach is pretty group dependent, but we've had fun with it.

Ulitharid's motivation: Since the ulitharid is the closest to a mastermind NPC in this scene – the elder brain being more monstrous – I'd ask myself why is it working so closely in tandem with the elder brain? My understanding of the lore is that there's usually tension there as the ulitharid is always one step away from pulling half the colony away from the elder brain to create their own underground empire (and eventually become an elder brain themself). More a lore-building question, but if you decide there is some tension there (e.g. maybe elder brain blames ulitharid's risky ambitions for recent githyanki attack), that might be a wedge the players could drive between illithid forces.

Stun-locking: I hinted at this, but with multiple INT saves risking stunning, it's very possible you will have half the party stunned each round. From my view, that's your biggest issue to design around. That can be a real drag, and I'd consider how you want to play that. One way I've gone is to create a sort of psychic dreamscape which stunned character can explore, allowing them to learn some lore and potentially discern weaknesses of the illithids. Another way I've gone is to provide a limited use resource (icky consumables called "psychic leeches") that counteract illithid stunning for a short duration like 3 rounds, but afterward you suffer 1 round vulnerability to psychic damage. Or if you have a highly tactical experienced group, they might factor this into their planning and devise their own countermeasures / adaptive response.

 

[Stalker0]

Sitting Duck issue / encounter distance: In the face of artillery/blaster superiority – which your party definitely has in spades – the elder brain could be a bit of a sitting duck. Definitely I'd set up the terrain/room so that the furthest a creature could be from the elder brain & still have line of sight to it would be 60 feet. In fact, since it's only reliably dangerous at 30 feet, I'd consider some kind of cover (or even a magical field or mucilaginous sphere) surrounding it at 30 feet away, so if you're outside of that area it's harder to affect the elder brain, but once inside (and thus within range of its tentacles) it's a normal attack/save.

I wanted to echo this, very important. No elder brain should ever be in a room where a player can attack them and not be in immediate range of the elder brain's attacks.

this is also a good time to have traps laid out. Considering the foreknowledge an elder brain normally has, it makes perfect sense to set up traps even in normally well traveled areas

 

[Trit One-Ear]

This is what I think I needed to hear. Thanks everyone. I keep looking at all the ways this will disrupt my party's "regular" tactics without considering the various other tricks they all have to recover. This tendency is probably why I have yet to really challenge my party with a Deadly encounter.

@Quickleaf thank you for the fantastic suggestions. My thoughts and responses to some of them below.

Creature Sense & defensive prep: Elder brain can sense creatures up to 5 miles away, so unless the players are taking special measures or have some plot mcguffin, the elder brain knows the party coming and should pursue additional recon (e.g. cranium rats) and make some defensive preparations.

Definitely going to factor this in. The joy of them investigating a mystery is the Elder Brain has been able to watch them for days on end, and will absolutely know they're coming. I just have to be sure to reflect this in the plans it makes.

Sitting Duck issue / encounter distance: In the face of artillery/blaster superiority – which your party definitely has in spades – the elder brain could be a bit of a sitting duck. Definitely I'd set up the terrain/room so that the furthest a creature could be from the elder brain & still have line of sight to it would be 60 feet. In fact, since it's only reliably dangerous at 30 feet, I'd consider some kind of cover (or even a magical field or mucilaginous sphere) surrounding it at 30 feet away, so if you're outside of that area it's harder to affect the elder brain, but once inside (and thus within range of its tentacles) it's a normal attack/save.

Very helpful to mark this (thank you to @Stalker0 as well for seconding that). I'll think about what kind of obstacle makes the most sense... honestly, probably a psionic field or barrier will be enough.

Cavernous terrain: I would look for an opportunity to showcase what is unique about the underground terrain in this particular area, and ideally make it advantage the illithids (at least initially). Something like "scream stone" formations which if it would take psychic damage emits a high-pitched magic negating/draining pulse.

This will also probably inform the defenses the Brain has. Maybe the screaming pillars break concentration? I'll probably cherry pick a feature from a different aberration and use it as a mechanic.

Thralls... use with caution ...possibly tie to Legendary Resistances: Since your party was just dealing with a murder scenario, IF you want to use thralls, I'd suggest building in some way to free them (or at least the most sympathetic of them) from the illithid control. Of course, players may want to turn their new-found allies against the illithids, so you might want to foreshadow a way to break the thrall-dom but temporarily incapacitating the victims.

I absolutely love this. I always like to use an in-world reason for a creature to have legendary resistance. Using the psionic energy of some captured locals to protect itself feels great, and it gives the heroes something to do if they'd like to strip away those LR charges without using spell slots. I recently learned loss of memory etc. is a Yellow Card/Veil for one of my players... so I'm already having to tip toe around this carefully, and as such am allowing many of the victims to be rescued with enough time, healing, and NPCs casting greater restoration, so I'm adjusting the lore a bit to make Mind Flayers a little less permanently-fatal.

Ulitharid's motivation: Since the ulitharid is the closest to a mastermind NPC in this scene – the elder brain being more monstrous – I'd ask myself why is it working so closely in tandem with the elder brain? My understanding of the lore is that there's usually tension there as the ulitharid is always one step away from pulling half the colony away from the elder brain to create their own underground empire (and eventually become an elder brain themself). More a lore-building question, but if you decide there is some tension there (e.g. maybe elder brain blames ulitharid's risky ambitions for recent githyanki attack), that might be a wedge the players could drive between illithid forces.

I have definitely been planning on having some conflict between the two factor in. My reasoning for the two working together is they both recognize the need for the other while the colony recovers from near-annihilation. That doesn't mean they work well together though. The ulitharid is absotlutely going to plane-shift away once it feels truly threatened, and I will build up to this with some RP in advance. Our party's Bard especially loves non-violent solutions, and if he wants to try and divide the two, by all means.

Stun-locking: I hinted at this, but with multiple INT saves risking stunning, it's very possible you will have half the party stunned each round. From my view, that's your biggest issue to design around. That can be a real drag, and I'd consider how you want to play that. One way I've gone is to create a sort of psychic dreamscape which stunned character can explore, allowing them to learn some lore and potentially discern weaknesses of the illithids. Another way I've gone is to provide a limited use resource (icky consumables called "psychic leeches") that counteract illithid stunning for a short duration like 3 rounds, but afterward you suffer 1 round vulnerability to psychic damage. Or if you have a highly tactical experienced group, they might factor this into their planning and devise their own countermeasures / adaptive response.

I've been worried about this and will definitely play with some ideas. The dreamscape idea is interesting, and could maybe factor in to how the players are able to free the thralls. Maybe during their stunned rounds they have to overcome some kinds of obstacles with skill checks, and after enough of those (using the Clocks System from Blades in the Dark), boom free a thrall.

Thanks again everyone for the help and advice. I feel a lot more clarity on how I can design this big encounter now.

Trit

 

[Quickleaf]

I've been worried about this and will definitely play with some ideas. The dreamscape idea is interesting, and could maybe factor in to how the players are able to free the thralls. Maybe during their stunned rounds they have to overcome some kinds of obstacles with skill checks, and after enough of those (using the Clocks System from Blades in the Dark), boom free a thrall.

Thanks again everyone for the help and advice. I feel a lot more clarity on how I can design this big encounter now.

Trit

Nice! That's a really elegant solution that ties several of those things together. Bravo.

 

[Trit One-Ear]

Hey all,

So my party FINALLY reached the Elder Brain lair, and we left on the reveal of the Brain as our cliff hanger.
I now have a week and a half left to fine-tune this encounter and... it's definitely looking rough for them atm.
They've gone through a few encounters to get here (including a pack of Bulettes that managed to KO the party bard, costing some valuable spell-slots), and are feeling a little worn out. But without taking a Short Rest, they have plunged into the lair.

The encounter is designed as such:

• The Elder Brain - Sitting in its pool atop a platform, it is a good distance from the party as the enter the chamber. It has protected itself with a psychic barrier that grants it 3/4 cover to all attacks more than 30ft. away from it. (I am debating giving the party something they can interact with, near the Brain of course, to disable the barrier.)
  • The Brain has 3x hostages currently in its pool that grant it its Legendary Resistance. The party can rescue them by pulling them from the pool, removing the LR charges.
• The Ulitharid - As the lieutenant, its job is to charge the heroes and protect the Brain. However, it values its own survival above the Brain's, and once below 1/3rd hp will planeshit away. Alternatively, it can be persuaded to leave earlier if the heroes see the antagonism between the two villains.
  • The party is discussing (in our time between sessions) fleeing to rest up and bring in reinforcements. That is absolutely an option, though the Brain will try to stop it if possible. I'm considering having the Ulitharid hold the stone door to the chamber closed using Telekinesis, which would at least give the heroes a chance to take out the other monsters before dealing with it.
• 3x Mind Flayers - I'm concerned 3 is too many, as the possibility for chain-stuns becomes an exponential problem the more threats there are. (One PC stunned is an issue, 3 is a huge problem etc.) I have devised things for Stunned/Dominated PC's to do while stunned (see below) but I still worry 3x will make the encounter too difficult (or at least too difficult to be fun). Maybe this can be balanced by the Ulitharid holding the door, or maybe I cut down to 2x.
• 5x Thralls - I have a number of thralls in the room, all creatures from the village nearby. There are 3x gnomes (CR 2), which should be pretty easy to handle. There are also 2x Leonin, one a Paladin-base, the other a Barbarian-base. They are CR 4 and 5 respectively.
  • While a hero is stunned or dominated, they will mentally be transported to a "psychic plane" where they can interact with other creatures stunned or dominated. If they choose, they can break the psychic chains (currently 3/creature) that hold them as thralls. Once broken, the creature is freed and can join the heroes' side.
  • Depending on how things are going, I may have Intellect Devourers burst forth from freed thralls, giving the heroes one last enemy to contend with. (This is something I will cut if the fight is going poorly.)
  • I want the Leonin at least to be strong enough that, if freed, they will be a strong enough addition to the heroes' side to be worth it. But that also means until they're freed, they're a pretty powerful threat themselves... maybe bringing their CRs down to 3 and 4 respectively would help.
• Hero Reinforcements - The heroes have sent word to the village nearby to send help when they can, so I have an ace-in-the-hole possible if things start going south fast. A few of the leonin royal guard, including an NPC they've befriended, can show up to help even the odds. Similarly/alternatively, a powerful spiritual leader's soul has been with them for the last two sessions (it's complicated) so perhaps he can summon some help as well.

So... all of that! A party of 6x Level 11 characters (short some resources) seem to have their work cut out for them. INT saves are not this party's strong suit, so that shifts the math slightly more against them as well.
In your opinion, have I prepped a TPK? Or is this going to be a satisfying victory over a truly threatening foe?

As always, input and comments deeply appreciated.
Trit

 

[jgsugden]

DM and PC strategy is a huge element in how difficult an encounter will be. I've TPKed a group with an "easy" encounter, and I've seen PCs laugh off something that was technically triple the deadly threshold.

Illithid are extremely intelligent (and wise), and extremely good at working together. They're going to know the PCs are coming, as well as their capabilities. You should have them prepare using all of their resources and capabilities. Your PCs are going at them on their home turf, when they're prepared, and when they know the team's capabilities. Using all of that to your advantage should make this an insanely difficult encounter With a CR 14, CR 9 and several CR 7s - all of which have the ability to do one or more 'Save or Suck' abilities.

 

[Trit One-Ear]

DM and PC strategy is a huge element in how difficult an encounter will be. I've TPKed a group with an "easy" encounter, and I've seen PCs laugh off something that was technically triple the deadly threshold.

Illithid are extremely intelligent (and wise), and extremely good at working together. They're going to know the PCs are coming, as well as their capabilities. You should have them prepare using all of their resources and capabilities. Your PCs are going at them on their home turf, when they're prepared, and when they know the team's capabilities. Using all of that to your advantage should make this an insanely difficult encounter With a CR 14, CR 9 and several CR 7s - all of which have the ability to do one or more 'Save or Suck' abilities.

This is in large part why I am concerned... I don't want to punish my party for taking these guys head-on. Our game up till now has been pretty forgiving in that sense, so I don't want them to feel blindsided by my suddenly penalizing them for not making big plans in advance.

Ultimately, I want them to succeed. I'd love for them to succeed in a high-stakes combat with these things. But maybe rewarding their plans to retreat and regroup is a better approach.