Really high magic levels

[Taqwus]

Interesting. Does Communion/Sabbath affect the MR bonus? (And magic duel as well)?

I've had casters with very high effective spell levels in battle, but mostly by making truly insane abuse of massed communicants, which can be counted by assorted hit-province / hit-much-of-battlefield spells. 'specially with the harder wards these days.

"Cast over and over" has somewhat limited use because the really high fatigue spells tend to be the ones that use lots of gems as well, and no matter how good a mage you are you can only carry a total of 30 (IIRC) magical resources.

There is quite a bit of potential goofiness to explore; e.g. I once had an squadron of Iron Dragons commanded by a GoR'd Iron Dragon. Experimenting with all the different globals as well; I tried Haunted Forest for the first time in a game with Man. I lost anyway (wasted way too much time dealing with Machaka and Pangaea while Ulm ate the rest of the Aran map as no other AIs were available to stop it), but that's a pretty funky spell.

Theme armies can be fun as well. In a Jotunheim/Utgard game I carried over from the demo, I finished my conquests with an atrociously expensive Army from Hell -- literally; it had all the Demon Lords, Ice Devils, Arch Devils, and one of the Heliophagii, and the Banefire Lord as well as the Father Illearth. Many of which had been empowered... ouch. Not efficient in terms of total slave/gem cost, but amusing to watch in battle.

[Whismerhill]

also you get increasing stats :
for example each fire magic skill increases attack rating (if I remember correctly)
and each earth magic skill increases protection (up to 20, if I remember correctly ;-) )

each air magic skill increases accuracy for any kind of projectiles (magic or not)

I think death magic increases the FEAR effect if you have one