When opening all 3 doors to the rooms in which Eriasudy should spawn, you will only trigger him once and then your stuck in the area. Seems like he´s triggered by opening the door and not by rinnung into the room or something. This is a major issue that should have been thought of before hand. If you have the option to play with 3 people, this is the first idea you have after memorizing Eriaudys spawn points.