Me and a couple of my guildies from The Covenant of Eitrigg found a little trick that will make your time in Heroic Grim Batol much much easier, especially on the first boss!
Well you're going to want to start off with your placement.

The general will also periodically summon adds by yelling the following: "Attack you cowardly vermin!" When this command is shouted, Trogg Dwellers will run down the mountain in the background. One of these adds has a debuff that makes him larger than the others and have a sickly purple glow around him.

One way to deal with the troggs is to kill them all and make sure the purple trogg is killed separately. Although, my guild mates and I have found a way to make this fight roughly 50% easier.

He also has an ability that when he reaches around 30% health he will get a debuff known as "Frenzy" which is an undispellable "soft enrage" which increases his attack speed by 50% and his Physical Damage by 50%. This is the point to pop cooldowns if you are having trouble.
Occasionally the boss will cast two more abilities known as Blitz, where he will select a random ranged party member and begin to cast Blitz after several seconds, you have approximately 5 seconds to get out of the way and then the boss will hit the spot you were previously at and continue to beat on the boss. If you are hit by Blitz on heroic, it is very likely, an "instant kill." The other ability is Ground Siege where he will target a random melee party member and begin to cast, to avoid this, you must move 20 yards away from the boss or else you will take critical damage from this ability, it is immediately safe to move back in after this spell.
After following this guide you should know all you need to know to kill the first boss in Heroic Grim Batol, happy raiding, enjoy the game, and always remember to stay away from the fire.