A mage knows 17 spells (arbitrary number). Can that mage cast any of those 17 spells or are they limited to selecting X number of spells per run? I'm not sure if it is like D&D, for instance, where a mage can have 10 first level spells in his spell book but can only memorize 5 of those spells at a time to use. I'm guessing the mage can cast any spell until they pass out from stun damage but am looking for clarification.