Brainlash

Brainlash is a ring.

Not so much a ring as a wrap designed to completely encase the wearer's index finger, a brainlash is formed of what appears to be a thin sheet of platinum laced with spidery gold webbing. Once slid over the finger, the covering becomes as flexible as cloth, but stays in place until the owner removes it. When a brainlash is first attached, no immediate effect occurs. Over the course of the next day, the wrapping slowly enhances its wearer's intellect by tapping his life force. At the conclusion of the 24-hour period, the bearer's intellect is increased, but his stamina is decreased. Once in this state, the brainlash cannot be removed easily. The wearer must will it to deactivate its power, returning the enhanced mental power to its normal place over the course of another day. At this point the wearer's attributes return to normal and the wrapping slips easily off the finger.

Source

 * This item can only be found in Zul'Farrak, and is considered extremely rare.
 * It has an extremely small chance of dropping from rare spawns, Executioners, and four of the named bosses.
 * While the diminished stamina can intimidate some, this ring can be used by Priests, Mages, Warlocks, Shamans, Druids and Hunters looking to boost their mana pools. For those that spend their time in parties or duoing, losing 100 HP is not a significant deterring to gaining 225 MP.