I think I did everything -- touched the glowing bush to get fungus, jumped in the murky pool, moved totems onto altars, moved bodies onto altars...Killed everything including the Shin Lord. BUT it wants me to kill the King next. I see no king anywhere in the dungeon. Ported back to the beginning, and nothing. Did find some Golden Trinket which gives gold-lust for a few seconds, but not sure as to the purpose. Found giant white crystal on top of pile in final room. Where is the king?
The king is in The Fabled Ruins of Guk: The Lower Corridors (Solo). You seem to be in Halls of the Fallen (Solo) which ends with Lord Kurpep. Maybe you were doing a weekly quest that requires you to kill both?