The Thorn Chest is a limited edition Chance Chest that was released on September 5th, 2014 and ended on September 8th, 2014. There is no new Epic released in the chest.
There is a 4x chance to get an Epic or Legendary armor.
Cost
1 Chest: 30 Gems
11 Chests: 300 Gems
40 Chests: 999 Gems
Guaranteed Bonus
11 Chests: 5 Air Fusion Boost Armors
40 Chests: 20 Air Fusion Boost Armors and a Death Shroud+