Checked, and partly fixed already. Gellar only comes out at night: the game's own encyclopedia describes him as another form of the Ragenon Souleater, who appears at the stone altar during the night, so the Gellar quest is a night quest. By day the Ragenon Souleater stands at the altar instead. The crowd of Harvested Souls around it was our mistake and is gone after the next server update; the Souleater calls two of them when he is hurt, as he should. Live after the next server update.
Fixed. Gellar is out from 22:00 to 4:00 on the game clock (type /time and look at Game Time, not your own clock). A game day lasts two real hours, so his night is half an hour in every two, and at 8:00 game time it is morning and the Ragenon Souleater holds the altar - that end time is the same as on the official servers. The Ragenon Souleater now calls two Harvested Souls at 75 %, 50 % and 25 % of his health, six in all. Live after the next server update.