The whole castle/Elona's dungeon quest is a major design flaw in D.D. : it's part of the main quest, so people will tend to try it early on, but once you step into the castle you ARE STUCK, No going back till you can get out of the dungeon, the VERY LONG, VERY TOUGH dungeon, that used up all my many heal and mana and restore portions (and I had a LOT going in).
Iona's dungeon has Health/Mana shrines near the start which give you a full restore and they replenish themselves pretty quickly.
