The Suntara Stones quest chain

The Suntara Stones is a quest chain where the player aids a wounded archaeologist, which leads to treachery and betrayal in the name of Ragnaros.

The Suntara Stones
At the bottom of the Grimesilt Dig Site, you find a wounded archaeologist, Dorius Stonetender. Apparently grievously injured by the nearby Dark Iron dwarves, he asks you to take him back to Ironforge.
 * Suntara Stones

You beat back the Dark Irons, and escort him out of the pit. You are only part-way to the Stonewrought Pass when you are ambushed by more of them, though, and Dorius takes a fatal hit.

You find a on his body, describing some variety of stones that someone called Lathoric the Black is using to enslave Dorius' excavation team, to complete something called Obsidion.
 * Suntara Stones (2)

You take the letter on to Ironforge, where you give it to Dorius' brother Thorius.

Thorius asks you to help him find vengeance and free Dorius' men. You make your way past dark iron dwarves in The Cauldron, through the Dark Iron Dwarves' mining works to The Slag Pit. Near the middle of one of the rooms, you find a Dying Archaeologist.
 * Dwarven Justice

The archaeologist tells you that a Mysterious Artifact (Searing Gorge) guarded by the Twilight's Hammer is being used to control the expedition members, and that placing it on the Altar of Suntara will break the control.
 * Release Them

You find the artifact in a pool of lava above Thorium Point, guarded by Twilight cultists. Dead cultists don't bother you, and some adroit leaping nets you the artifact without too much contact with the lava itself.

... but no sooner is the artifact placed on the altar (after yet another trip down into the Slag Pit) when who should appear but Dorius, risen from the dead and calling himself Lathoric the Black. He monologues about how Ragnaros directed him to build Obsidion, a golem, to destroy the Blackrock orcs.
 * Rise, Obsidion!

While destroying the power of the Blackrock orcs might be laudable, Dorius is clearly in the grip of even more evil and powerful forces. It takes considerable effort, but you manage to defeat both Lathoric and Obsidion, and return significant parts of both to Thorius.