Power Mask is one of the three skins released in the second part of the MadJawZ's Shop offer. It could be purchased as part of an item deal in mid June 2018.
Power Mask could be purchased for $9.99 in a limited time deal that included 16000 coins. It was not available for individual purchase and may not be available for purchase in the future.
Details of this skin may vary depending on location, platform or time.
Note: The second part of the MadJawZ's Shop offer was released again for a limited time in early March 2020. The price and included coins for Power Mask remained the same.