The rarity of Secrets of the Merqueen is Mythical, and been equipped it takes a “Bundle” slot. At this moment the item is available for trade.
Secrets of the Merqueen is a skin for Death Prophet. The skin was added to the game on January 8, 2016, it was created by sandviper.
Secrets of the Merqueen is currently one of the most popular skins, but it is rarely seen in the game due to its high price.