A epic witch chest is an item in Evony TKR (The King's Return). It can be found after killing certain monsters or bosses, with some of them listed below.
The description of Epic Witch Chest in Evony TKR says:
Open the package to gain all the items in it.
Epic Witch Chest is known to drop from a number of bosses or monsters upon killing, including Witch.
Note: This list may be incomplete.
Epic Witch Chest opens up to all of the following items: