20-foot long intelligent centipedes with blue poison dripping from their mandibles, and spell resistance. Their poison makes their victims forget the last few moments of their lives. Bred by Derro, they were forced to eat the cytillish fungus that grows in their Underdark caverns. They can also flash their fungus once a day to inflict others with a blast that stuns them and takes their memory.
First Reference: Chapter 166
Other Notable References: Chapter 167