Thorn has converted the cast command to use the new spell system. If you want to know more: read some info about magic
The current spells have been converted. So all we have for now is what we already had, falling into the categories mysticism and sorcery.
Soon, there will be spells for necromancy and enchantment. Until then, those trainers are not yet giving any initial skill.
Also, it seems magic no longer works during combat. Thorn will fix that soon.