No idea on spells, sorry, I chose to go through as Melee first. I found the Dolls pretty useless, they die very fast and don't do much damage at all.
Normally in DD the spells that will work well on the highest level critters are Blind, Freeze, and HellSpike. If you remember the small room in DD where you are attacked by a gazillion Dwarves and a Black Ring boss, it was just Blind and Freeze the Boss and Hellspike the whole room for the win. I have not researched the BD spells though.
Good Luck
