Infernando is one of the five skins released in the Day of the Dead offer. It could be individually purchased using game coins in October 2016.
Infernando could be purchased in the Skins Shop under the 'Day of the Dead' tab for 2900 coins. It was available for a limited time and may not be available for purchase in the future.
Details of this offer can vary depending on location, platform or time.
Note: Infernando was released again for a limited time under the Skulls of Agario offer in early March 2021. This time Infernando could be purchased for 3200 coins.