ToME WikiNo spoilers here, please. NO SPOILERS HERE!
Warning: As of ToME version 2.2.7, Runecraft is more or less broken. Beware!
Instead of using spellbooks like the other spellcasters they instead use mystic runes. To cast a spell they select a primary rune of the elements, fire, cold, etc. and they also chose a set of secondary runes, which shape the effect of the first one. The secondary runes include Self, Arrow, Ray, ... and Armageddon. After that they chose the amount of mana to use and the spell is cast! But the more secondary runes they chose the more mana is used to cast the spell. They also are bad fighters, but if they concentrate all their mana in one spell (especially with a mage staff of mana) they could kill nearly anything.
Starting stat modifiers, starting Skills, innate abilities and starting equipment: Please see the in-game help.