Potentially Gamebreaking One-Shot Method-Requires Expert Players (Patreon)

The Cataclysm Firelands raid contains a boss called Baleroc who puts a buff on you called "Blazing Glory". Blazing Glory increases both damage taken and player maximum health by 20%. This stacks up to 30 times. 

Blazing Glory survives, very temporarily ie no more than a few seconds, into an instance. This does not seem to be inclusive of loading time-ie you'll always get a few seconds regardless of how long the loading screen takes. It is possible to port out of the Firelands and into an instance.

Methods such as the monk's "Touch Of Death" ability, which does 50% of the monk's maximum health, become very overpowered temporarily, potentially doing tens of millions of damage or possibly even hundreds for very well-geared players 

To exploit this is not trivial, you will need to set up a scenario where one or more players can be ported directly to a boss and execute such an ability instantaneously. This requires patience, familiarity with the Baleroc fight and a knowledge of how to optimize loading screens (hint: once you have ported into an instance during a session, when you leave it and return much of the code has been saved and it will load faster). Warning: when attempting this you'll likely get frustrated at first. Nonetheless for a disciplined team there is the potential to trivialize even the hardest mythic fights. 

To the newer player this type of exploit may seem too hard to pull off: in fact since I've started exploiting numerous teams have told me of their success executing this type of play (especially during mop when half a dozen teams were using my icicles method). Most just do this for the gear but some have made RL money greatly reducing the difficulty and time involved in boosting.