Disharmony of Flame requires you to slay Overmaster Pyron.
This is a prerequisite for both 
[52] Commander Gor'shak and [54] The Last Element. Turning this quest in will cause both Vivian Lagrave and Galamav the Marksman to whisper you, and their two questlines will become available.
Objectives[]
Travel to the quarry in Blackrock Mountain and slay Overmaster Pyron. Return to Thunderheart when you have completed this assignment.
[52 Elite] Overmaster Pyron slain
Description[]
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. End the disruption and return to me.
Reward[]
You will receive:1
55
Completion[]
This cannot be... it must not be. The destruction of Pyron has merely lifted a veil. Within the depths of Blackrock is a much more insidious source of corruption.
Gains[]
Upon completion of this quest you will gain:
- 5100 XP (or 30 at level 70)
- 250 reputation with Thunder Bluff
Quest progression[]
- [52] Disharmony of Flame
- [56] Disharmony of Fire
Notes[]
This is not what you might expect for a 51 Elite. This Mob hits VERY hard and has 11,004 hp. Take a healer and 2 dps types and do not expect to win lower than level 52.