Monster Analysis: Mind Flayers and the Elder Brain

  • Illithid First Appearance: 03 Strange Bedfellows
  • Armor Class 15
  • Darkvision 120 ft, Passive 16
  • Speed 30 ft
  • Advantage on saves vs. spells
  • Average/Max HP: 71, 117
  • ep04: 79 taken, 8 dagger to the maw by Vax
  • ep07: 90 taken, 8 dagger to the eye by Vax 
  • ep09: 94 taken, 20 Fireball by Tiberius
  • ep13: 86 taken, 8 poison dagger by Vax

Mind flayers (also known as the illithid) are psionic tyrants, who have a long, long history of subjugating entire races of humanoids as slaves to their empires across dimensions. The eventual resistance from their thralls eventually forced those who took residence on the material plane to settle in the Underdark, where their schemes to reclaim their former holds.

Illithid value the power (and taste) of the mind. Their entire hivemind network is founded in telepathic communication and psionic abilities (rather than the arcane). They subsist on humanoid brains for sustenance, using the enzymes and psychic energies to fuel their own bodies. They also occasionally will save a brain to be turned into intellect devourers, which are used to hunt and obtain more brains. Their ability to devour brains (and subsequently kill without saving throws) caused them to often be the first target for the respectfully terrified Vox Machina.

Illithid are willing to allow their thralls to complete their physical work for them, especially when a foe proves more powerful than anticipate and a hasty retreat is in order. The mind flayers Vox Machina encountered seemed somewhat more willing to do their own dirty work, but frequently exercised their daily Plane Shift when battles turned unfavorably.

  • Elder Brain First Appearance: 10 K’Varn Revealed
  • Armor Class 18 (at weakest), 20 (before party flees)
  • 320 damage taken and “not on death’s door yet”

The Elder Brain is the collection of brains from all of the colony’s past generations of mind flayers. The center of the hivemind, it telepathically directs all illithid within 5 miles of it, and is capable of holding a complete mental conversation with each individual mind flayer at once. It has its own psychic field that keeps it in position and deflects attacks. It can also defend itself offensively by a physic pulse (which, thankfully, the party was just out of range for it to be effective).

The sheer volume of it, built by generations of illithid brains, made it an extremely potent and extremely hardy being to take out. The difficulty is amped when the party is under the time pressure of hundreds of illithid looking to both defend their heritage and claim a celebratory meal in their new-found independence. While the Elder Brain is probably significantly weakened (one would hope after it has been smashed, ripped apart, dehydrated, fireballed, and shot multiple times with bullets and arrows), as Taliesin said: “It’s never going to forget us!”

Of course, none of these describe a certain mind flayer who might be considered the savior of the illithid despite being cast out for his arcane persuasion…