Baldur's Gate 3 - Feed the Mind Flayer Quest Guide (Act 3)

Feed the Mind Flayer Quest

Screaming can be heard from the abandoned windmill in Rivington (X:44, Y:-32). Lockpicking the old rusty door allows the party to investigate. A hatch leads to the windmill basement, with an unconscious Mind Flayer within.

Abandoned Windmill

Interacting with the Mind Flayer provides the following choices:

It doesn’t feel very fortunate.
Wake the newborn mind flayer.
Attack the creature before it wakes up.
[STEALTH] Sneak away.

Choosing to attack the creature immediately starts combat with a level 8 mind flayer. Killing it provides a Mind Flayer Brain, which can be consumed, as well as a Windmill Key, Ring of Truthfulness, Bloodstone, and Absolute Orders: Newborn. Consuming the brain grants one illithid potential.

If the player chooses to wake the newborn, they can hear its demands.

What do you need?
Was it you I heard screaming when I entered the windmill?
Attack!
Leave

It needs a fresh brain to feed on. This can be responded to in a multitude of ways:

I’ll see what I can do.
I can fetch you a corpse, freshly killed. Brain intact.
I never work for free.
[PERSUASION] Go find your own meal! Even weakened you’re more powerful than anything out there.
I’m not going to bring you food.

Suitable Corpses

Dead Refugee which can be fed to the Mind Flayer.

If the party agrees to help the Mind Flayer, they need to find a corpse. Any random corpse will do, including killing random NPCs. Previously existing corpses will also work.

Some options include:

Dead Refugee near the Ironforge Gnome hideout (X:45, Y:66)
Brilgor buried behind the Open Hand Temple (X:-106, Y:-19)
Father Lorgan in the Open Hand Temple (X:-57, Y:-22)
Ffion Goldgrind on the upper levels of Fraygo’s Flophouse (X:-13, Y:76)

The party needs to pick up the corpse and bring it back to the Mind Flayer. After which, he unlocks one illithid potential.

If the Mind Flayer is persuaded to get its own meal, it simply leaves the windmill to go hunt.

Quest Rewards

An additional point for the Illithid skill tree, either gifted from the Mindflayer or consumed from the Mindflayer brain. The Mindflayer can still be killed for its brain after giving it a corpse, but consuming it will not grant an additional Illithid skill point.

Notes

If you feed the mindflayer and let it live, it will leave the windmill after a long rest. It will re-appear in the Lower City killing a couple of NPCs.