This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Travel to the quarry in Blackrock Mountain and slay Overmaster Pyron. Return to Thunderheart when you have completed this assignment.
The elders have felt a disturbance amongst the elements. The Dark Iron dwarves have summoned a foul spirit into our world that threatens to plague our lands with an eternal draught. This disharmony of flame must be investigated.
Travel to Blackrock Mountain, through the Chasm of Flame, into the quarry. It is there that you shall find this lord of fire: Overmaster Pyron.