Adder's Cloak

Adder's Cloak is a superior-quality style item unique to the 2011 St. Patrick's Day event, Mxyzptlk's Mischief. Use of the item unlocks the Celtic Snake back costume style.

Source
The Adder's Cloak can obtained as a drop from story arc bosses during the 2011 St. Patrick's Day event.

Style unlock
Upon using the Adder's Cloak, a character unlocks the Celtic Snake back costume style, which can be accessed at any time from the Style Window.


 * Celtic Snake