I'm not sure about the sha being "one if its heads."
If I recall, wasn't Y'shaarj, or however you spell it, assumed to be dead until this point in time? Garrosh is filled with Pride so we have the manifestation of the Sha coming because of him, however thats not whats corrupting him, NOR why they are choosing to defend him.
Why would the Paragon encounter be number 13 but the Sha Encounter be number 3? Doesn't make sense. What happened is that Garrosh found this Old Gods heart, who happens to be the Klaxxi's God, and is being slowly corrupted by the god to become his shell for the mortal world.
TL;DR - Garrosh is being turned into an Old god so the God can "live" again and the Klaxxi are stopping us from killing him cause the Old god is their god and creator.
More specifically, I think the dungeon journal says that you will always be fighting 3 (until you are down to the final 2 and then the last one), but at the end of the fight you will have defeated all 9.
3 start out active. As you defeat one, it will grant an ability to a member of your raid, the other 2 will heal, and one on the bench will join the fight against you. Repeat that process 9 times, and you win.
Garrosh has Y'shaarj's heart, the klaxxi want it back to ressurect him or something. They see you as a threat in their path, so they try to kill you. Probably.
The Shas are the "shadows" of the heads. They are not the heads themselves. Shadow is clearly a metaphor... or perhaps, more accurately it's an attempt at describing something that's very hard to describe, like a ghost. These "heads" may also be a metaphor like different faces or aspects of one being-- of course, we are talking about an Old God, and, though all our experience so far has been that Old Gods are mostly eye-centric, it wouldn't be surprising if he actually had 7 heads.
The Klaxxi warred against the Queen because her corruption was causing her to act in a way that was detrimental to the natural cycle of the mantid, which the paragons and klaxxi were created to uphold. That's why I'm not too broken up about killing them, they were never good guys. They wanted to return the Mantid to normal, which includes trying to swarm over pandaria every few generations and worshipping old gods.
Sha of Pride has nothing to do with Klaxxi encounter in SoO. They are there because of Heart of Y'Shaarj, which Garrosh retrieved from Vale.
---------- Post added 2013-06-15 at 07:31 AM ----------
They started the war on empress because she sent the Swarm on the Wall before its time.
It's not really a plot-hole, as explained above. The Paragons view the Sha as mere shadows of Y'shaarj, not worthy of worship. Only with the presence of the Horde/Alliance conflict did they become strong enough to even be a threat. Y'shaarj himself, however, is strong regardless, and the Klaxxi view him as worthy of their worship because of it.
3DS Friend Code: 0146-9205-4817. Could show as either Chris or Chrysia.
The Klaxxi are charged with protecting the future of the entire Mantid race from a Queen whose bidding contradicts their ways, WHATEVER THE REASON. The Paragons speak of another Queen who tried to hold back their race from combat and prevent the culling of the weak and the eventual strengthening of their kind. Shek'zeer was going to wipe out their race in suicidal attacks and was committing other violations, like using mutagenic science on any Mantid at all instead of proven veterans.
And as others have said, the Sha are just shadows. Y'Shaaraj is who they follow, and it is he who is imprisoned in the Titan device recovered during the Dark Heart of Pandaria scenario. And the Dungeon Journal for Garrosh makes it plain that as he absorbs more and more power, he becomes progressively corrupted until he effectively IS Y'shaaraj manifested in a new avatar. Whether the Mantid are seeking to follow Y'Shaaraj through Garrosh or recover the Old God's essence, they end up opposed to us.
The most hilarious thing ever is that when races/cultures/populations act realistically (as in they have their myths, and they sometimes act irrationally / without sound logic) and have internal conflicts it's considered poor writing.
What real-life culture acts in a way that is wholly consistent with a set of rules / principles / logic / rationality ? None. Things get mucked up, and there is tension in attempts at reconciliation.
I am the one who knocks ... because I need your permission to enter.
Well I see 2 different reasons to why we fight the Klaxxi Paragons.
The first is that they believe that Garrosh is the true manifestation of Y'Shaaraj. And since that is basicly their god/deity/leader they will follow him to the death.
The other is that they believe Garrosh is using the heart of Y'Shaaraj for the wrong purposes and they want to take it for themselves. When we show up they see us as a threat to their plan and wants to get rid of us.
Best guess is that want the heart and have come for it and we need to stop them from getting it
I really doubt they are there to help garrosh
they prolly want the heart to put in there little museum with other y'shaarj memorabilia and they think by having the heart they can charge 20 gold to mantid tourists
The way I see it is like this. Destroying but not killing something as powerful as an Old God has a lot of side effects. We're seeing that in game as the Sha. Call it background radiation left by the destruction of the immensely powerful Old God that over time and because of the nature of the being that caused it started to manifest as the sha. Vastly weaker than the old god but still powerful in their own right.
The Klaxxi worship the old gods and we can either assume they are coming to try and grab the heart as its part of their deity or they see Garrosh as being an avatar of said old god.
As someone who is still leveling through Pandaria, I had a question: where does Garrosh get Y'sharrj's power from? I'm assuming it's explained in the Dark Heart of Pandaria scenario, tho I kind of don't want to assume too much right now.
In the containment unit? -_-
Because old gods cannot be killed (permanently at least) when Y'Shaarj's body was destroyed, his "life force" was sealed in the pandora's box to prevent him from infuencing anything or fleeing to another dimension (old gods are multidimensional beings). Shas probably weren't a concern at the time, because there weren't any creatures with free will and/or emotions around.