"Siege of Orgrimmar is after Throne of Thunder the last raid instance in the Mists of Pandaria expansion. It will feature fourteen bosses. It will be split up into wings, so it will not be as linear and straightforward as Throne of Thunder, meaning you can choose what bosses you're going to kill after you bring down the initial set."
I guess after you do the first 4, you can pick whatever bosses you want in "Gates of Retribution" or "The Underhold", but I've not played the PTR at all, so maybe someone with experience can elaborate.
Last edited by IRunSoFarAway; 2013-09-09 at 12:16 AM.
There are very few choices, for instance I believe after Spoils of Pandaria, you can do Thok or Blackfuse, or even Paragons (maybe?) in whatever order you like. Definitely Thok or Blackfuse. But that's it.