Mind Flayer

The Mind Flayer is a humanoid creature with purplish-blue skin, an octopus-like head, and four slithering tentacles.

Encounters
The Mind Flayer can be found on all floors of the dungeon. It is somewhat difficult to kill. Apart from the evil necromancer and perhaps the beholder, it might be the rarest monster. If you listen, you will hear a "Squishing, sucking, slithering sound."

Strategy
The Mind Flayer is an advanced monster. It can cast a Psionic Mind Blast at you, which requires you to roll a 13 or higher on a Intelligence check to avoid. If it hits you, it can do up to 20 points of damage.