Creatures now have magical resistances of the following categories: fire, ice, earth, wind, psychic, holy, and unholy. Creatures differ from each other and some may be more resistant than other. Generally speaking, for every resistance a creature has, it has an equal susceptibility in another area. For example, goblins are resistant to fire but are prone to aether magic.
All of the special trainable mage/wizard spells are live on the new spell damage vs. NPC resistances, but there are clerical and other spells that have not yet been adjusted and there are currently no adjustments for players (you guys don't have magical resistances yet).
Now it makes more sense to specialize in one magical area versus another. Enjoy!