Aer is the main source of energy in the game Tales of Vesperia. Aer is needed for Blastia to work. It is also needed to cast magic. Aer is produces by aer krenes, and the levels of aer is controlled by the Entelexeia. Aer usually invisible unless in extreme quantities.
 Effects of Aer
In small quantities, Aer is harmless; in fact it's all over the world. However, in large quantities, it can have serious effects on health. In humans, their body's metabolism accelerates, causing fatigue and head pain.
For plants, their metabolism also increases, resulting in them growing to epic proportions.
Monsters exposed to huge amounts of aer causes them to panic.
Entelexeia who intake to much aer will go out of control. Such in the case of Gusios. All of the aer that an Entelexeia intake over their life span takes a solid form after they die. The solidfied aer becomes known as apatheia.