G.N.E.R.D. Rage

G.N.E.R.D. Rage is related to the seasonal world event Hallow's End. Completing this achievement is criteria for the meta achievement Hallowed Be Thy Name.

Location
Consuming G.N.E.R.D.S. gives you the buff needed to complete this achievement. They can be found within a Handful of Treats. Before Patch 4.2, the G.N.E.R.D.S. buff would last for 30 minutes, and could stack up to 4 times. Now, the duration lasts for 5 minutes and does not stack.

It should be noted that Tol Barad does not allow eating while the battle is going on, so you should consume your G.N.E.R.D.S. before the battle begins.