Just to be different (and yet totally honest) here's my favourite three (based on regularity of use as well as all being personal favourites).
1: Heroic Might.
2: Bloodlust.
3: Bless
Alright, so some of you might not call these attack spells but when each party member is sporting those beloved three icons (along with an almost constant Merlin's Shield in Cet's Pyramid and the surrounding area). they can deal out a fair ammount of damage.
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Balgin, the Dwarf