Adventurer who thinks the fancy anti-psionic amulet around his neck will protect him from Illithids, completely forgetting that just one of its tentacles has more strength than he has in both arms.
He’s actually shocked when the Mind Flayer overpowers him and strips away his armor, forcing him to the ground so that it can rape him with its prehensile tentacle-dicks while it feeds from his skull. After slicing through his parietal bones, it leisurely devours his brain one lobe at a time, making sure it’s struggling prey is conscious for as long as possible, savoring the taste of cortisol and adrenaline as the adventurer’s endocrine system floods his body with stress hormones.
Eventually, the Flayer’s prey’s body will start to give up, and that’s when it can hook into the adventurer’s nervous system with one of its tentacles. It’s a crude form of control but it’s enough to make the man’s body convulse rhythmically, tightening around the tentacle-cocks writhing in his guts. The stimulation carries the Mind Flayer over the edge, and it allows itself to consume what’s left of the brain as it climaxes.