the body of his avatar was eaten by demons apparently thats why when guldan went inside it he was then eaten by the demons that were there
"I was a normal baby for 30 seconds, then ninjas stole my mamma" - Deadpool
"so what do we do?" "well jack, you stand there and say 'gee rocket raccoon I'm so glad you brought that Unfeasibly large cannon with you..' and i go like this BRAKKA BRAKKA BRAKKA" - Rocket Raccoon
In the lore of war of the ancients Sargeras "ceased to be" in a physical sense when the portal collapsed as he stepped through and he has been disembodied ever since.
To have Sargeras rebuilt with a new titan body and flung back into the universe as head of the legion would be truly awesome.
So what if .... The voices that came through Wrathion was the voice of N'goth or an old god.
So the we are the old gods and their servants. So the twilight hammer's cult, instectoid races,
and faceless ones rebuilding Sargeras' body or his avatar. They want him back on Azeroth to
cause chaos because they love it and/or it would make it easier for them to take over after
he was done with it. Sort of the enemy of my enemy is friend type deal.
Old gods + Burning legion = WIN
It was also made clear that Sargeras would not stand any chance against the unleashed Old gods. That´s why that was a pretty safe plan for the Old gods.
They wanted Azshara to open a portal for the Legion and Sargeras so that the Legion can release them.
Maybe they want that now too. You know that vision Wrathion saw could be an Old God that whispers to him like they already did with his dad Neltharion.
According to the books Sargeras body was shattered after the destruction of the Well and so maybe this "last titan" Wrathion tells us about is Sargeras and the Old gods really want to reconstruct his body or something.
Kinda wondering what the mogu were sent to Pandaria for, since Wrathion suggests it was a specific task. Intruiging.
Kinda figuring Sargeras went bad partly because he figured the titans weren't up to the challenge of stopping the Old Gods.
Makes the greater cosmic struggle more interesting that way - the titans want order, the Old Gods want chaos, and the burning legion want annihilation.
It is mentioned that when they are freed the combined might of all the old gods would destroy Sargeras and his legion. Not sure if that is true or if the old gods are just being overconfident like all villains.
They would be so big and mighty that Sargeras would flee or beg for mercy. Many titans were needed to fight the Old gods and they were no way less powerful than Sargeras (of course he was the titan champion).
After all Sargeras is "just" a single Titan and would not stand a chance against the freed Old gods ... never ever.
So he wouldn't mind shattering their prisons and giving the azeroth as his thank you present to them.
So Old gods trying to rebuild a HUGE Titan body some where.
Who is up for some green flaming tentacles ?
Maybe the Old gods and Sargeras made a deal so that his body is reconstructed in exchange to freeing the Old gods from their prison.
My bet is the legion.
Personally I'd rather the old gods weren't involved as well, I hate them showing up so much.
Too often, we are mistaken for druidic types. perhaps that's true for some shaman, but do not let yourself be plagued by the ignorant belief that we are always peaceful.
Nothing about what I do is harmonious. I command the elements to my will. There is nothing offered in return. I would have it no other way.
Never assume an ogre's stupid, that's when they'll get you.
There are only 2 plausible characters that could have spoken through wrathion in this scene.
2. Old gods (N´zoth)
My bet is on Kil´jaeden to be honest. Makes much sense that he seeks help in reconstructing his boss Sargeras.