Wraith Chest is a limited edition chest. The epic that was introduced was the Specter's Shroud. There was a 3x chance for Legendary and Epic.
Cost[]
1 Chest: 30 Gems
11 Chests: 300 Gems
40 Chests: 999 Gems
Guaranteed Bonus[]
Buying 11 chests at once: you get 5 Spirit Fusion Boost Armors
Buying 40 chests at once: you get 20 Spirit Fusion Boost Armors and a Soulshard Raiment +