In the fortress instance of Grim Batol there are only two achievements that you need to complete for the Glory of the Cataclysm Hero achievement. They are found at the first and last bosses and called Umbrage for Umbriss and Dont Need to Break Eggs to Make an Omelette.
This achievement is only slightly harder than the easiest ones due to the ease of accidentally killing the infected too early, and the difficulty of healing the tank if the buff is left up too long. Done properly the fight is not too difficult though.
The trogg that has the disease is the purple one that spawns with the 3 normal ones. As soon as it spawns someone needs to pull it aside and CC it until much later in the fight. Good choices here are hunters with ice trap, mages with poly, or even druids with root. Once the infected purple trogg has been moved aside and CCed the fight progresses as normal, with the tank saving all his cooldowns for the next part of the fight.
The fight changes from the normal plan at about 10-15% health left on Umbriss. At this point the tank should move the boss next to the infected and CCed trogg and DPS switches to the trogg to kill it off. This will give Umbriss the trogg disease, buffing him to cause 50% additional damage. The tank then starts popping his cooldowns in sequence while DPS kills the boss. The healer will also want to have any cooldowns that they have ready to help keep the tank alive as damage will be extreme. If timed right though, you should have less than 10% of the bosses health left to deal with and be able to down him in less time than the tank's cooldowns last.
This achievement is not really anything special. While some groups ignore the basic mechanics of this fight and brute force it down, to earn the achievement you need to do the fight the way it is meant to be done. This means that after each time the boss casts eye of the storm and the two faceless corruptors are summoned, that players be in position and ready for them.
Since the corrupters can not be rooted or CCed it is not possible to completely stop them. However, any slow effect you have will affect them and must be applied as soon as they spawn. Some of the slow effects that will work include Chains of Ice, Frost Traps, Crippling Poison, Hamstring, Earthbind Totem, Wingclip, and more. To make things run smoothly, make sure you assign which player will be slowing which add (right or left) as they come out.
Once both are slowed, DPS should first focus on one, then the other, all the time keeping both under slow effects. The key here is to ensure players know which add they are to slow, and which add is to be focused down first. Once everyone is coordinated, the fight should be easy.
As long as you have 3 solid heroic geared DPS players, 2 of which have slow effects, and you get to the adds as soon as they spawn it should not be an issue. While you can potentially do this with the healer or tank applying slow effects it will be slightly harder as the tank would need to be moving around and therefore potentially take hits in the back and suffer higher damage.
You can return the to main guide page here: Glory of the Cataclysm Hero Achievement Guide.
To read the latest guides, news, and features you can visit our World of Warcraft Game Page.