Reins of the Azure Drake
Where you'll find it The Azure Drake is dropped by Malygos on the 25-man version of the encounter, but this wasn't a mount I saw all that frequently even during Wrath. Even if you allow for the low drop rate, this didn't make much sense -- the Azure Drake is a really pretty mount -- and I suspect that, at least on my realm, the 25-man Malygos was never a really popular encounter. The vehicle mechanic made it annoying to pug reliably, even past the point that Blizzard allowed for vehicles to scale with gear.
I'm afraid Malygos might be doomed to be one of the least-revisited raid encounters as a result, which is kind of a shame. It was a pretty unique fight, and then there was the minor matter of being able to faceroll phase three with a one-button macro for the drake vehicles ...
Drop rate 1%
Reins of the Onyxian Drake
Onyxia was one of the more popular soloing targets until Blizzard revamped her as a cool little "birthday present" for WoW's fifth anniversary.
Where you'll find it Dropped by -- who else? -- Onyxia, though only in her Dustwallow Marsh locale; you won't find it off the version you'll see in tier 11's Blackwing Descent. The mount looks kind of like an adolescent version of her and was another popular ninja target.
Drop rate 0.7-1%
Where you'll find it Above Mimiron's neck. Ha ha! I kid. If only it were that easy. Mimiron's Head was once a 100% drop off the 25-man version of the Yogg-0 encounter, which made #10 on our list of the 25 most evil achievements in the game and took the best guilds in the world the better part of four months to manage.
Drop rate 1%. At 85, you should have the DPS necessary to trivialize just about everything on the encounter apart from the Insanity mechanic, although you'll probably be blowing through adds, tentacles, and Yogg himself quickly enough that even that won't be much of a problem. Good luck!
Also the subject of And I'll Form the Head!, a feat of strength.
Where you'll find it The Crimson Deathcharger is technically not a drop but a reward from a quest that happens if you kill the Lich King in Icecrown Citadel under special circumstances. If there's a player in the raid wielding Shadowmourne, Arthas will drop an Unsealed Chest containing five items that start quests. One of the items in question is Alexandros' Soul Shard, which starts the quest Mograine's Reunion. The reward from this is the Reins of the Crimson Deathcharger, which is a death knight's 100% ground mount with red trappings.
Drop rate N/A. The drama came from the inevitable fight over who got the various rewards, and this was another issue that showed up in our inbox from time to time. Putting a Shadowmourne together required a lot of assistance from your fellow raiders, and not everyone was on board with giving the whole megillah to an already-privileged player rocking what was acknowledged as a hugely overpowered legendary.
Lorewise, Invincible is one of the more interesting mounts in the game: You're riding the resurrected horse of one of the world's biggest baddies, and you don't get much cooler transportation than that.
Where you'll find it Dropped by Arthas in the 25-man version of heroic Icecrown Citadel.
Drop rate Invincible was once a guaranteed drop off each heroic Arthas kill (and that was the goddamn least that Blizzard could do for you after the nightmare that that fight was ... do I sound bitter?), but now it's probably in the region of a 1% drop.
Also the subject of Invincible's Reins, a feat of strength.
Drake of the South Wind
Where you'll find it The Drake of the South Wind is dropped by Al'Akir in the Throne of the Four Winds. It shares a model with the other "Wind" drakes available from early Cataclysm content, including the raiders' Drake of the East Wind, the Altairus drop we saw last week, and the West Wind drake you can get at exalted with Baradin's Wardens/Hellscream's Reach.
Drop rate Wowhead lists it as slightly more than a 1% drop rate.
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