Way back in the 1.0 elemental spells were split into Ubral, fire, lightning, and ice, and then Astral water, wind, and earth. Originally conjurer had all of them, but with the remake of the classes, they gave Umral to thaumaturge and Astral to conjurer. Aero is a dot spell, not much damage up front, but over time it can add up, it's also instant cast.