The Frozen Flame

Video Guide: https://www.youtube.com/watch?v=7ltytVOOAZo

1. The Frozen Flame (Scenario)
• Accept the quest, The Frozen Flame, from [npc=99415] at coords 28.6, 37.2 (Dalaran Crater in Hillsbrad Foothills).
• Click on [npc=99418] to be transported to [zone=7695].

Stage 1 - The Frozen Halls
• Travel north to coords 76.8, 61.8, traveling toward the [npc=98760], who is casting [spell=198484].
- - While traveling north, defeat the [npc=98571] and [npc=98570] mobs.
- - The [spell=198484] will effect either the left and right side or the center. Try to move down a path uneffected by this spell by walking down the border between the center and left/right side.
- - Avoid coming in close proximity to the [npc=99605], as a mob will come out of it, if you do.
• Defeat the [npc=98760].
- - After you begin attacking it, it will no longer cast [spell=198484].
- - Avoid standing in [spell=198525].

Stage 2 - Meltdown
• After killing [npc=98760], destroy the [npc=102105], blocking your way.
• Travel the passageways to 74, 53, while avoiding falling ice.
- - As you follow the corridors, kill any mobs you come across, and avoid [npc=99605].
- - Destroy the [npc=105377] at 74.2, 52.8.
• Continue to 64, 53.
- - Destroy the [npc=105378] at 62.8, 53.8.
• Continue to 53, 40.
- - Defeat the [npc=98590], and its friends.
- - Destroy the [npc=105379] at 52.6, 39.4.

Stage 3 - Hot On The Trail
• After destroying the final [npc=105379], enter the next room and defeat the group of [npc=99723].
- - Avoid letting the group get too close, as they will cast [spell=198550].
• On the second wave, defeat the pair of [npc=99614].
• The final wave, involves killing [npc=99700].

Stage 4 - Playing With Fire
• After defeating [npc=99700], travel north to 51.8, 23.3.
• Defeat [npc=99615].
- - When [npc=99615] reaches 50%, she will cast [spell=194360], making her immune to damage; and she will summon [npc=98686].
- - When [npc=98686] casts [spell=198608], move out of the way.
• After [npc=98686] is defeated, [npc=99615] will lose the buff [spell=194360] and once again be killable.

Stage 5 - The Flamestrike (Final Stage)
• Pick up your artifact weapon, [npc=103696] from 51.6, 16.6.
• [npc=99763] will create a [npc=99861] to [zone=7502] for you to step through.
• After arriving in [zone=7502], enter the Violet Citadel, and turn in the quest to [npc=90418].

NOTE: Contrary to information listed in Wowhead, this quest is active, and was reborn with the Legion expansion.

If you happen to disconnect or leave the scenario for any reason, you can get back to it by going to the Dalaran crater once more - there should be a portal waiting there for you.

Wowhead is reporting this quest as not being in-game because it's *original* version was removed way back in the days of Wrath. Most of the quests being created today are numbered 39000+, so a quest ID of 11997 is quite odd for an artifact-related questline. Originally, this quest was in the Grizzly Hills, with [npc=26875] sending you to meet [npc=26212]:

The Westfall Brigade has been dispatched to the northeastern part of Grizzly Hills to secure passage for our troops. They have established a base camp to the northeast of Grizzlemaw, and to the southwest of Thor Modan.

You might recognize the brigade's leader, Captain Gryan Stoutmantle as an honored veteran of the war against the Scourge in Lordaeron. But the people of Westfall know him best for his decision to leave the battlefield and return home to take on the Defias.

It seems to have been replaced by Report to Gryan Stoutmantle... Again with slightly different wording. Blizzard renamed this quest (at some point between introducing it back in Wrath and reissuing it in Legion) to "REUSE", and it seems that they finally got around to reusing it.