ToME: the Tales of Maj'Eyal

Just started playing the game, and I've been wanting to try the "instinctive" magic casting classes, but run into the problem of running out of magic and then just being stuck for the rest of the dungeon. The only thing I've run into that seems to replenish mana is the manasurge rune that comes with archmages, but I have no mana regeneration at all to multiply.

A manasurge rune will give you some mana regen while resting, so you can fill up after each fight using one of those (it's a passive benefit of equiping one).
Other then that, just keep an eye out for items with +mana regen on them, and learn the skills those classes get which provide mana recovery when you can.