Ragnarok is one of the two skins released under the Doomsday offer. It could be purchased as part of an item deal in late April 2021.
Ragnarok could be purchased for $12.99 in a limited time deal that included 12000 coins and 1300 DNA. It was not available for individual purchase and may not be available for purchase in the future.
Details of this offer may vary depending on location, platform or time.
Note: The Doomsday offer was released again for a limited time in late September 2021. The item deal with the Ragnarok skin remained unchanged for this release.