Mark of Norgannon

Source
This item can be found inside Alexstrasza's Gift after defeating Malygos in the 25-man version of the Eye of Eternity.

Effective haste
If used every cooldown this item grants: 136 * 20 / 120 + 18 = 136 * 1 / 6  + 18 = 136 / 6 + 18 = 40+  2 ⁄ 3 Haste