Neltharions Lair is a dungeon whose entrance is located in Highmountain in the World of Warcraft game. The minimum level for this dungeon is 100. The main anagonist race in this dungeon are Drogba. The dungeon contains 4 bosses. The end boss of Neltharions Lair is Dargrul the Underking.
Neltharion's Lair forms the end of the Highmountain questline which sees you go up against Dargul, the Underking. Those who haven't played the game before, Neltharion is also know as Deathwing. Deathwing was the main antagonist in the Cataclysm expansion. Neltharion was a large dragon who broke free from his underground prison and sought revenge on the planet, changing the landscape forever. The only time you see Neltharion is through flashback quests in the Highmountain quest line.
Rokmora is a giant rock monster that is awoken from underground when you reach the boss. He'll be summoned by a NPC so don't worry about it. He's an easy boss, the difference between the normal and heroic levels is that he'll create a large area of damage that you will need to mitigate and move out of the way from.
When you reach this boss, he'll be standing on a ledge high above as you can see from the screenshot. Clear the trash that is round the area before engaging the boss, its easier that way. Ularogg will jump down when the fight starts. His main weapon is his staff.
During the fight, he'll disappear and giant stone totems will appear in his place. You need to destroy one of the totems for him to reappear. The amount of times that the totem will appear will be dependant on how long you take to kill him.
Naraxas is the giant worm at the back of the room. Clear the trash before you engage this boss. The main things to be worried about is to move out of the way from when he spits his green acid. The melee dps will need to move the most but the ranged dps, if you're at a safe distance, it shouldn't be too much.
Once you have killed the boss, you need to run and fall down the hole. At the bottom of the hole is a pool of water so you won't kill yourself. Also at the bottom is the loot.
Dargul is the main antagonist in the Highmountain quest line and this is where you finish him once and for all. Remember to clear the trash but if you're high enough and fancy a challenge, take on both Dargul and the trash.
There are two things to be worried about here, the first is the giant lava monster that he summons. The monster will follow someone around the area but the monster is easily defeated. If you're skilled enough, you won't need to kill the creature, you just take on Dargul.
The second thing you need to worry about is if you're not high enough, is that he'll create rock spikes which you'll need to hide behind to prevent being damaged from the AOE.