If you have the spell Silence Daria will be a piece of cake. When you start the fight morph into a more powerful form then cast the spell "Silence" so she can't use mind drain or Minor healing. If you don't beat her right off the bat re-cast silence when it wears off.

To get some easy exp in the castle fight, all the elephants you find they give you a lot of expierience

In the town after the castle levels, walk behind all the houses instead of on the street. You will find potions a scrolls behind them.