I very often use earth magic: resurrection, raising the dead, slowing, antimagic, and of course, explosion! And there's nothing to say about the city portal – it's one of the most useful spells!
Also, air magic (acceleration, chain lightning);
and I almost never use fire magic (except for Berserk – it saved many battles), although there is such a powerful spell as Armageddon;
water magic is also important, especially healing, blessing, and prayer, as well as clone.