Patch 3.2: Argent Coliseum raid story and encounters (SPOILERS)

There's been a lot of speculation as to what Patch 3.2's new raid instance, the Argent Coliseum, will contain. We got a taste of what bosses we might fight a little while back when the 3.2 PTR launched and some Achievement information was datamined, but I've taken it all one step further.
As with my previous post on the 5-man content in the Coliseum, I've datamined a ton of information from the PTR game files, including NPC and spell data (another massive thanks to Boubouille of MMO-Champion for his help), to determine not only who we're facing up against (for sure), but how exactly the encounters will go down once we've gotten our epicly-clad heinies into the octagon Coliseum.
The same disclaimer as last time applies. The encounters could change at any time, datamining isn't an exact science, I could be misinterpreting files, etc, etc. But I'm pretty solid on what I've written down, and anything I'm speculating on will be noted as such.
Any spell or ability listed in this guide will likely be a random rank, given the spell database's knack for throwing me 10-man and 25-man spells in the same area! Don't assume that the damage values are accurate until you get killed by them!
Remember: MASSIVE SPOILERS AHEAD!
Ready? Let's go!

Well, these aren't really final, of course, as we're going to be discussing and responding to what we saw at 



