Better have something to cure the dot he and the sneak have for you, or you'll watch yourself die after you kill him.
As you enter Harbringers, you turn right and run down that hall to the corner room just past Toiler Opanin spawn. there are four discordlings that spawn there; facing the room with Toiler Opaning spawn to your back, he spawns back right corner of the room; "a discordling sneak" spawns front left in the same room.
These two are usually over-looked, since the names start with "a discordling", yet they have some of the better drops here (void the annoying "Girplan's Tail").