Method and Paragon have both re-cleared 13/14H and are now progressing on Garrosh. How long do you think it will take one of them (or perhaps another guild) to kill this boss world first?
Here is some background:
Lei Shen lasted 7 days after the world first heroic twin consorts kill.
Sha of Fear lasted 4 days after the world first heroic Lei Shi kill.
Spine of Deathwing lasted 11 days (somewhat irrelevant)
Ragnaros lasted 13 days after the world first heroic Majordomo kill.