A cousin to the rot grub, the Brain Parasite is similarly a 1-inch long vermin found in carrion, dung, and other such garbage and organic material. Burrowing into the flesh when contact is made with unhygienic conditions, it releases an anesthetic to avoid detection. A Wisdom check will reveal it burrowing under the skin, at which point there will be 2 rounds to burn or cut it out before it gets to the brain, either of which method kills the parasite and causes 2d6 points of damage to the host. After this point a cure disease spell will be the only way to save them.

Where the brain parasite differs from the rot grub, however, is that it burrows into the brain rather than the heart, and hibernates there. The victim will behave normally until encountering a carnivorous monster, at which point they will attempt to be slain by that monster (via an uncontrollable urge to be close to said monster and not defend oneself) so that the brain parasite can fertilize its eggs in the new monster’s feces. Should the character fail to be slain by the first monster it sees, they will continue trying at the next opportunity until cured or killed.