We recently discovered a small exploit with the Malygos fight, while doing the 10 man version of it, trying to get the 6 minute achievement. It *should* work on 25 man as well.
Basically, it allows rogues and mages to control drakes in Phase *one* and *two* (!) of the fight. This is great for guilds who are struggling a bit with DPS or healing in Phase 1, making it quicker to pass by. Also, I could imagine it would greatly help getting the 6 minute achievement.
Anyways, in order for this exploit you work and be able to control a drake in phase one or two, you MUST be a Rogue or a Mage. We tried this in various ways, but could only get this to work with those 2. It *might* work with Shadowmeld as well, but since we're horde, we can't say this.
Basically, you do the fight as normal as possible. During transition from phase two to phase 3 (where Malygos shatters the ground, and all players mount up on red drakes) rogues and mages can vanish/cast invisibility. This has to be done *before* the ground is shattered. Don't do anything that brings you out of vanish/invisibility. As soon as everyone is on a drake, all OTHER players inmediately dismount, while the rogues and mages on their drakes inmediately move away as far away from Malygos as possible in order not to get back in combat. Since the rogues and mages weren't in combat when Malygos shattered the floor, he will not engage and kill them If they get somehow in combat before that however, Malygos WILL kill those players too.
If done properly, all but the mages and rogues are dead, Malygos will reset and quickly disappear, while the concerned rogues/mages will still remain on their drakes. They can thus use all their drake abilities in the next attempt, either heal or DPS.
Anyways, it worked great for us, so I thought I could post it here as well.