Magic immunity? I'm sure I defeated that with magic. Took me a while to get it just right, but practice practice till I did, and seem to remember it involved two casts of a secret life drain spell, then just run into said boss.

The boss is immune to quite a lot of spells. Not all of them but the fight was still much much harder for magic based character than for melee warrior.
See above ;)

My favourite thing was, when I completed Throne of Baal with wizard, to import the character into BG1 and start the game with him.
I had way more fun then I should have with obliterating Xvarts with High Level Spells, starting encounter and then stopping time, casting some AOE spell and tehn fleeiing to the other corner of map like I had nothing to do with it before enemy could even do anything.
It felt awesome. :-) In case it is an ad for a hairbrush I see nothing wrong with it. :-)

King's Bounty series.
It's a mix between strategy and RPG. At later stages you can win battles without losing even one single unit.

Rage of Mages series.
An action-RPG. Great mage equipment at later stages and spells, which become more powerful with you leveling up.

Master of Magic

If you don't mind the dated visuals and sound (and the AI cheating like hell on higher levels), this is the ultimate Mage 4X game... Endless customisation options for wildly varying playing styles, and a beautiful power progression through the game from little sparks to apocalyptic destruction...