Haha! This is too easy!
Vaga vs. Thaxll'ssillyia
Prebuffs: Spirit Armor, Stoneskin, Mirror Image.
Things went pretty smoothly this time around. Since I didn't have any spells to break through his protections, I had to wait until they wore off, then I began casting PfMW myself. After a bit of time went by and 4-5 Lower Resistances later, I started unleashing a few Fireballs, all up until he hit me with his breath weapon, blinded me, and reduced me to 4th level. Good thing my PfMW was still up and running, and using my last Fireball scroll, the black beastie went down.
Ahhh, sweet sweet victory