ben> Wound and Divine Thud hasten the monsters to their inevitable meeting with God.
Seriously, the only spells you absolutely need in BoE are Unlock and Move Mountains. Without the rest, things can get pretty frigging hard, but without those two, a lot of scenarios are outright impossible.
Oh, and I'll side with Creator's recommendation of Areni, there. I'd recommend NTH, but its system of invoking elemental spirits trapped in runes is probably closer to actual 'witchcraft' than the game magic of Exile.
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Personally, if you're tied to sort of stuff, you should play Blades of Avernum instead - I can see an all-fighter party being much less frustrating there.