Kromog is the final encounter in The Black Forge wing in BRF.

For a more detailed view of his abilities or loot, please view the in-game dungeon journal or click HERE to view at WoWHEAD.

This encounter is a single phase encounter, with all this abilities pretty much on a timer.  Managing your range from the boss to dodge mechanics and properly DPS-ing extra crap during his primary ability of Rune of Grasping Earth/Thundering Blows is key.

Abilities/Overview

Warped Armor - Reduces movement speed by 15% and increases phys dmg taken by 20%.  Stacks up to 5. Tank swap mechanic.

Stone Breath - Mild nature dmg breath, deals dmg every second for the duration.  Also casts on the raid if there are no targets in melee.

Fists of Stone - deals heavy phys dmg to the tank.  The dmg is split evenly between players (up to 2) within 15 yards.  In other words, tank and OT stack.

Slam - Long cast ability, slams fists on the ground, deals "massive" phys dmg to the raid.  Amount of dmg decreases the further away you are from boss.

Rippling Smash - Cascading eruption that deals heavy nature dmg to those it hits.  Targets ranged only, stay at/close to max range to dodge this.

Rune of Crushing Earth - Large red rune will spawn under random ranged player, and 2 large hands will spawn on either side of it.  Either over time or when a player "trips" the rune, the hands will slam together dealing heavy dmg and stunning for 5 seconds.  In Beta, the hands only triggered when there were 2 of these Runes/Hands up and they both triggered at the same time.

Reverberations - Any time his fists slam the ground, or certain abilities are triggered, yellow sound reverberations will spawn from him towards the back of the room, dealing moderate dmg to those they come into contact with.  Think MUCH smaller rings from Atramedes from BRD.  Advised to dodge these.  However, they can be soaked if a player has an immunity, etc.  But should be easier to dodge.

Shattered Earth - mild nature dmg dealt to 4 random players.  Just deal with it.

Rune of Grasping Earth - Yellow runes will spawn from the middle to the back of the room.  Standing in these runes will allow hands to grab the players.  This will deal very light nature dmg every sec, but will increase in dmg over time, but you will also be completely immune from all Physical dmg and will be rooted to the ground.  It is necessary to stand in these to counter Thundering Blows.  You need to slowly dps your way out of these and ONLY break them once Thundering Blows is over.

Thundering Blows - For the duration of RoGE, Kromog will repeatedly slam the ground, knocking anyone who isnt grabbed by a hand far up into the air, dealing moderate/heavy dmg to them every sec.  This is a wipe mechanic.  As if you dont die from the damage while you are up in the air, you will die from the fall damage.

Summary

Tanks stack, face boss either left or right, melee stack on opposite side.  Tank swap when appropriate, probably 3-4 stacks of Warped Armor.  melee MIGHT need to run out for Slam due to their proximity to the boss.  Ranged stay grouped (loosely) at/near max range to dodge Rippling Smash and also to be able to move out of Rune of Crushing Earth and dodge RS.  Everyone do your best to dodge Reverberations.  When yellow runes spawn for Rune of Grasphing Earth, everyone stand in a rune (1 per person), let tanks get in those closest to boss.  Slowly kill your and others Hands they are trapped in, healers should help dps this too early on as the nature dmg shouldnt be too severe at the start.  ONLY break out of these hands RIGHT when Thundering Blows ends.  Rinse-repeat.

TLDR/Saedo's Cliffs Notes

Most of this is just avoid the damage, watch the vid to recognize the stuff.

One twist is the Rune of Grasping Earth, get in those, 1 player each, they do some nature damage to you, but make you immune to physical damage.  That lets you avoid the Thundering Blows, massive damage that throws you up into the air.   But, you also have to kill the hands to release you afterward, and help release the tanks and healers asap.