O.o Iiiiiii should note that Ashardalon is a Red Dragon with a Balor implanted in place of his heart, so he is immune to fire damage. 

EDIT: While the holy element would be helpful, you would be hard pressed in the initial fight. You should factor in your monster level into your type level. And you don't have to got 15 levels into your base monster type.

You can add more equipment if you want.