Done! The game was a breeze after level 40 - this is where the Mage ends up being more powerful than the Warrior, IMO. I had four Flaming Eyes scrolls so I saved them up for Zigaldis, the big lizard whose name I've forgotten, and Bhaal. Also plenty of other Wandering scrolls to give me ridiculous stats of 35 Attack, 33 Defense and 60 Intellect for the last few battles. I managed to get my leadership up to 32,000 with Flaming Eyes, which is much lower than the 47,000 I had for with the Warrior.
But it didn't matter. Against Bhaal, my spellbook usage was Haste + Geyser in turn 1, then Stone Skin x 2 on turn 2, followed by more Stone Skin, Divine Armor, Magic Shield and Geysers when Bhaal brought more demons across. I managed to screw up my first try at this though - you really do need to preserve a stack of Scoffer Imps if you can for the long resurrection. On my second try, I was preserving a stack of Scoffers until Bill Gilbert's Archers shot them just before they flew off the burning ledge.
I was so annoyed and I thought I would have to start again. After killing Bhaal all there was left was 7 Demons, so I tried without much luck to run around the map having slowed the Demons, trying to resurrect. It wasn't working. Then the Demons spawned 11 Scoffer Imps, and I've never been happier to see those Imps in my life!

Killed the Demons and used Calm Rage to stock up on Mana for Resurrection. No problem - zero losses.
In general I found the Mage quite a bit harder in the earlier stages. You really have serious leadership issues on Impossible as a Mage, and it's not until past level 45 that you've really reached your full potential as a spellcaster. I just smashed my way through Elon and Reha with Geyser, which is insanely powerful when you have 50 Intellect. (About 5000-6000 damage x 8 stacks)
I just improved on my score by about 25 or so, but it's still in the 1400s as I took until day 28 again. I just can't keep the time down. That's the one thing I can't do with this game.
I was surprised to see that Archmages did the most damage, 22.5% This is because of the two Dresses of the Magess I had, which must be the best item in the game for a Mage. +4 Intellect, +800 leadership and +30% Critical chance for Archmages is insanely good. Two of them were enough that the Archmages ended up with a 95% Critical chance.
Oh well, it's been fun but it's really time for a break from KB:AP. I've been playing this so much over the last month it's caused marital stress. My wife is not happy. But I've had more fun playing the King's Bounty series over the past 15 months than I've had with any other game in the past ten years
And I literally mean that. I never thought anything would top Master of Orion 1 + 2 and Jagged Alliance 2 for me, but King's Bounty is just as good as those great games of the past.