Or better yet, how about getting rid of Marla Flamewing, too, so we won't have to fight anybody at all?
While this can be soloed, it may take quite a while, depending on your school. It's easier to go with a group or hire Henchmen. If you insist on doing it alone, make use of your minion.
I did this quest as a Myth school wizard and had a VERY easy time using spells like minotaur and earthquake, but my who is from the Fire school couldn't beat it without my help even after trying 3 times, also the myth minion helped as well. I honestly don't know how any other school could do it without decking out so good luck, maybe ask a friend.
I have soloed this quest with Balance, Death, Myth and Life wizards.
I did this much the same as I did Mavra. I used Fire Elf (or the poison on the Death wiz) to remove their defense shields and took out the protection pox first. I found this so much easier than Mavra.
On the wizards that didn't have these spells, I bought treasure cards. Lots of fire elf treasure cards in the bazaar.