Last session I threw this little beastie at the party at the finale of Doom of The Savage King. I stuck in the Jarl’s head. So here you go terrorize the PC’s with the Octobrain.
Octobrains are mysterious and ancient race bound to the forces of Chaos. They appear as a writhing mass of tentacles with the a brain at the center. Octobrains move by using their tentacles spring, usually towards a new host.

Init: +4; AC; 12; HD: 2d6; HP: 7; MV: 15’ (jumping); ACT: 1d20; SC: Fort: +1; Ref: +3; Will: +4

Atk: Face Hug: Make DC 3d6 Ref Save to avoid or it starts face hugging. On the following rounds make opposed Str Check against Octobrain (+2). If successful then the Octobrain has been removed. If fail then the Octobrain has pried open the character’s mouth, oozed inside their skull and begins absorbing the victim’s brain. The victim 1d5 Int damage each round. When the character reaches 0 Int then the character is dead and the Octobrain is in control and can access all of the dead character’s abilities. Attacks against a face-hugging Octobrain do half damage to the character it is attached to.

Other attacks:
PSI Shriek (once per day) 30 foot radius centered on the Octobrain. Take 2d4 damage. DC 12 Will Save for half.

Brain Bolt: One Target, 30 feet, DC:12 Will Save or take 1d4+1 damage.