MUSER’S MENAGERIE 6 – Brain Collectors for Dungeons & Dragons 5th Edition

Since they play such a significant role in one of the later Iron Gods adventure path chapters, I thought I would take this week to convert the sinister Brain Collector (or Neh-Thalggu) from the Pathfinder roleplaying game into 5th Edition Dungeons & Dragons.

I should also acknowledge that my long history of running the Call of Cthulhu RPG leaves me with a love of tentacled alien monstrosities from beyond the stars, so I was pretty excited to bring these critters into my own 5E games.

With that brief intro out of the way, let’s get to the cerebral hoarders!

Brain Collector
Large aberration, chaotic evil
Armor Class 16 (natural armor)
Hit Points 127 (15d10 + 45)
Speed 10 ft., fly 40 ft.
STR 20 (+5) DEX 15 (+2) CON 16 (+3) INT 19 (+4) WIS 17 (+3) CHA 17 (+3)
Saving Throws: Int +7, Wis +6, Cha +6
: Arcana +7, Insight +6, Perception +6, Stealth +5
Damage Resistance bludgeoning, piercing, and slashing from nonmagical weapons
Condition Immunities charmed, frightened
darkvision 60 ft., passive Perception 16
Languages: Common, Abyssal, Aklo, Draconic, Protean, Uncommon, telepathy 100 ft.,
Challenge 8 (3,900 XP)
Brain Collection. The brain collector can store up to ten humanoid brains and use them to enhance its knowledge and power. The destruction of these brains causes the brain collector to lose some of its magical power. Each brain can be attacked (AC 20: 15 hit points). Destroying a single brain deals no damage to the brain collector, but causes it to lose 1d4 unused spellcasting slots, starting with the highest level.
Cerebral Power (Recharge 6). The brain collector uses the power of its collected brains to supercharge its magic. The brain collector can use this ability as a bonus action to cause the target of one of its spells to make any saving throws against the spell at disadvantage.
Magic Resistance.
The brain collector has advantage on saving throws against spells and other magical effects.
Spellcasting. The brain collector is a 10th-level spellcaster. Its spellcasting ability is Intelligence (save DC 15, +7 to hit with spell attacks). The brain collector has the following spells known:
Cantrips (at will): acid splash, dancing lights, fire bolt, mage hand, minor illusion, prestidigitation
1st level (4 slots): detect magic, ray of sickness, shield
2nd level (3 slots): hold person, invisibility, mirror image
3rd level (3 slots): counterspell, lightning bolt 
4th level (3 slot): confusion, polymorph
5th level (2 slots): dominate person
The brain collector makes three attacks: one with its bite and two with its claws.
Bite Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) piercing damage, and the target must succeed on a DC 15 Constitution saving throw or be poisoned for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Claw Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.
Collect Brain. Melee Weapon Attack: +8 to hit, reach 5 ft., one incapacitated humanoid grappled by the brain collector. Hit: The target takes 55 (10d10) slashing damage. If this damage reduces the target to 0 hit points, the brain collector kills the target by extracting and collecting its brain.

I have been gaming long enough to have been first exposed to the brain collector in the old Basic Dungeons & Dragons sourcebook, the Creature Catalogue, though, when I did a little research while preparing this conversion, I learned that these monstrosities first appeared in the Basic D&D adventure, Castle Amber.


However, since I never had the chance to play Castle Amber, nor do I own a copy, I decided to dig out my copy of the Creature Catalogue to provide some old-school inspiration while doing my conversion.

Now, while I remember seeing the brain collector in the Creature Catalogue, I didn’t ever use one in an adventure, back in the day, largely because the art for it looked like this:

Comparing both versions, it turns out that the brain collector from Basic D&D and the version in the Pathfinder RPG are pretty close, thematically. Both of them are unspeakably alien creatures from “beyond the stars” that yank the brains from their victims and use them to fuel the brain collector’s spellcasting, which is pretty freakin’ cool and should serve as a “judging a book by its cover” lesson for me.

Since the brain collector’s abilities have remained so consistent throughout the editions, I decided it was important to try and keep those same signature abilities in the 5E version.

When I first decided to put numbers to the concept, I figured it would be a matter of reskinning a mind flayer, whose role the brain collector seems to play in Pathfinder, but I was pretty far off in that assessment.

Where the mind flayer is more of a ranged, mage-type foe, the brain-collector is closer to a tank or brute type critter (high AC and high hit points) that also has a host of nasty spells to unleash on its foes. Therefore, I ended up looking to something a bit beefier to serve as a starting point for the brain collector (I ended up using the Green Slaad).

Most of the abilities I ended up creating for the brain collector are pretty straightforward, but I wanted to write a quick word or two about the brain collecting. Initially, I thought that I would use the rules for 5E sorcerer class’ Metamagic to simulate the brain collector’s use of “brain power” to boost spells, but I decided that it would introduce too much book keeping for the monster (something that 5E has decidedly moved away from with its monster designs). In the end, I used 5E’s “recharge” mechanic to simulate this ability in a more streamlined way.

As for the brains themselves, I wanted to make them a tempting target for the players to attack (you cannot have “brains” in the name and feature “brains under glass” in the critter’s art and not expect players to want to smash those brains), but not so crippling that they’d prove to be a glass jaw for the brain collector (technically, glass brains, I suppose).

Finally, for the critter’s eponymous ability, I used the 5E mind flayer’s ability as a model to simulate the brain collector’s ability to pop open a target’s head Pez-style and yank out the brain.

Since the target has to be both incapacitated and grappled, I do not see this happened too often in combat, but that fits with how the brain collector has always been presented (the brain collecting seems to always be a story element that happens after combat ends).

That said, I felt it was worth including a “collect brain” ability on the off chance that the opportunity presents itself for the critter to add to its collection.

While it is not technically reskinning, these stats could be used to represent a shock trooper minion used by mind flayers against their enemies.

Alternatively, it may represent a horror created by a mad alchemist.

I cannot wait to use this critter against my players! The brain collector’s a beast in melee and has a host of interesting spells that can make life painful for the PCs (invisibility, polymorph, dominate person). When my players fell one of these things, it should really feel like an achievement.

I hope that other DMs out there enjoy fielding these as adversaries as much as I hope to!

Until next time, I remain;

MUSER’S MENAGERIE 6 – Brain Collectors for Dungeons & Dragons 5th Edition

5 thoughts on “MUSER’S MENAGERIE 6 – Brain Collectors for Dungeons & Dragons 5th Edition

  1. Nice conversion. I think I’ll steal it as is for my 5e game. Though I plan on making the Dominion base essentially a mind flayer of Thoon setup with the big bad being a flayer these guys will be perfect as muscle for them. I ran castle Amber back in the day but don’t recall this monster. Will need to reread the module.


    1. Thanks for the kind words Solomani, I’d love to hear how they play at your table!

      By the by, I love your boss fight write-up for Hellion. Pretty sure I am going to steal that for when I run Lords of Rust. 🙂


      1. Thanks! I have version 2.0 done now but not published. I want to run it with my characters before publishing it and see how it goes. They should face Hellion this week. Last night they took out Kulgara and the rest of the flunkies on that floor (and dominated Draiga which was good for them since they had exhausted most of their resources and 5e Draiga would have keeled them… most likely anyway).


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