Did all 3 parts-- IWD, HoW, ToL, and I'm somewhat disappointed... Behlifet was the hardest of the three bosses mainly because you can't start buffed and because, for some reason, I couldn't get spells to register on him at all... so I just buffed myself up to the max (potions + spells) while running around the outside of outer edge of the room to avoid traps, then killed him with weapons instead after taking out the cornugons and iron golems. On the other hand, Icasaracht was a pretty run-of-the-mill fight-- buff up ahead of time, click through dialogue, cast Lower Resistance, pelt with AoE spells to take her and the fish-people out, destroy magic bubble, the end. Luremaster was even easier-- went down with a single Disintegrate spell, game over. I did initially hit a roadblock when I got to Yxonumei (high MR, couldn't stand toe-to-toe with her at that point due to lack of sufficient buffing spells/slots for them), so I just went and did HoW and ToL at that point, then came back later and mopped the floor with her. One thing I noticed that kinda sucked is that I didn't gain any extra attacks from using Haste or Oil of Speed... I noticed a similar issue when I killed Drizzt in BG1 with my solo single-classed mage as well, so I'm guessing it must be an Infinity Engine thing... even if it doesn't make any sense.