Not yet observed in the beta: the Forever client retains this item's record without its stats. Those are sent by the server in-game.Until someone records it, the Classic tooltip is shown below. Forever has reviewed every dungeon's loot, so changes are expected.
In Classic Era, dropped by Lord Hel'nurath, Dire Maul West(22%).
Classic 1.15.9.69722
Diabolic Mantle
Binds when picked up
ShoulderCloth
66 Armor
+16 Stamina
Requires Level 57
Equip: Restores 8 mana per 5 sec.
Sell Price: 1g 61s 62c
Forever Beta 1.60.1.70009
This item does not exist in the Forever client.