Yrberop always listened to a music that only it could hear, but because of Zuggtmoy, people could hear a faint echo of its internal cacophony. Yrberop was enthusiastic about Phylo's plans to spread the will of Zuggtmoy throughout the Underdark. Due to its madness, Yrberop forgot all conversations after they ended.
Yrberop was the leader of the Circle of Sporers in Neverlight Grove. Yrberop was easily seduced during the Rage of Demons when Zuggtmoy's will twisted most of the Circle. It began creating more and more myconid sprouts.