Glory of the Firelands Raider is the legacy Cataclysm Firelands meta-achievement, added in patch 4.2.0 and worth 25 achievement points. It is not one of the current-tier Midnight raid metas: it lives in the old Firelands raid, entered at Sulfuron Spire in Mount Hyjal. Completing all 12 listed achievements awards the Corrupted Egg of Millagazor, which teaches the Corrupted Fire Hawk flying mount.
The 12 criteria are six heroic boss kills, Heroic: Beth'tilac, Heroic: Shannox, Heroic: Baleroc, Heroic: Lord Rhyolith, Heroic: Alysrazor and Heroic: Majordomo Fandral Staghelm, plus six mechanic feats: Death from Above, Do a Barrel Roll!, Share the Pain, Not an Ambi-Turner, Bucket List and Only the Penitent. Heroic: Ragnaros is not on the list.
How long it really takes: Firelands is soloable at modern max level, and a clean specialist run clears the whole meta inside a single weekly lockout, around 2 hours. Only the Penitent is the finicky one and wants a high-mobility class. Firelands runs one weekly lockout per character covering 10-man and 25-man, normal and heroic together, so a botched attempt on a boss that is already dead waits for the Tuesday reset. Budget a second week if a pull goes sideways.
Flametalon of Alysrazor is a separate prize, not the meta reward: a random Alysrazor drop reported at roughly 2-4% per kill, one roll per character per week. Heroic Ragnaros drops the Smoldering Egg of Millagazor. Extra booked hours go into those mount rolls once the meta is done.
Account-wide: the meta went account-wide in patch 5.0.4 and every WoW mount is account-wide once learned. Priced as honest time: 2 hours for $26.99, 4 for $53.99, 6 for $80.99, 10 for $134.99, with longer campaigns booked as repeat blocks at the same hourly rate. US is selected by default and EU has its own independent ladder. Manual play only on timesaver.gg, scheduled in ET or PT.
