The Warlocks Mantle is a Unique tier Equipment item under the "Arms" category. It is found in chests dropped by The Doom of Caeranthil.

It has the innate talent Overflowing Dam, causing your M1 attacks to deal 10% more damage while your Ether bar is full. If you have less than 40 Intelligence, Overflowing Dam's damage bonus will be halved to 5%.
Random Stats Aswell