Aer is one of the four skins released under the Titan Wars offer. It looks like a swirling tornado with lightning and a face. Aer could be purchased individually using game coins in November 2016.
Aer could be purchased in the Skins Shop under the ‘Titan’ tab for 2900 coins. This skin was available for a limited time and may not be available for purchase in the future.
Note: The Titan Wars offer with the Aer skin was released again for a limited time in early March 2018. The price for Aer was the same at 2900 coins.
Details of this offer can vary depending on location, platform or time.