The Maple Leaf Chest is a Limited Edition Chance chest that started on June 27th, and ended on June 29th, 2014.
It is a 3x Chest, and the new Epic released in the chest is the Earthwarden's Shroud , which is a Spirit/Earth Epic.
This chest may be a reference to Canada Day, which is on July 1st, 2014..
11 Chests: 300 Gems
40 Chests: 999 Gems
11 Chests: 5 Spirit Fusion Boost Armor