Mirrorball

Mirrorball is a Legendary Source for the  in Diablo III. It requires character level 31 to drop.

Mirrorball is known for effectively doubling (or tripling) the effectiveness of Magic Missile. The additional missiles fly in the same direction, with slightly different angle, effectively in the same way as Split rune of the said skill. With Split rune, only adds 1-2 more missiles, to the total of 4-5 per cast.

Trivia

 * The description appears to be a reference to the Tall Man's signature weapon, floating metal orbs, featured in the Phantasm movie series.
 * Mirrorball is a common term for a disco ball.