Is he currently inside the Embassy on the PTR?
Either way this dude better be present throughout Battle for Azeroth. This guy has been detrimental since MoP and it was a huge let down to briefly see him in Legion.
"In some ways, the Burning Legion's massive third invasion was ultimately Wrathion's fault. The invasion only occurred thanks to the alternate Gul'dan discovering and being sent to Azeroth, neither of which would have happened had Wrathion left Garrosh in prison. While the Legion would have returned regardless, Wrathion's manipulations cost Azeroth numerous lives against the Iron Horde, Primals, Breakers and other enemies; all lives who could've been better spent fighting the Legion."
Wrathion was the initial one to mention Argus the Unmaker indirectly during Mists of Pandara:
Wrathion says: Ahh - the heart of a king. The powers of a God.
Anduin Wrynn says: What are you doing? You're not seriously going to eat that-
Wrathion says: It is filled with Titan magic, the language of creation...
Wrathion eats the heart and goes into a trance.
Wrathion says: Oh, I see them - a million, million worlds - glittering in their perfection - but one above all others - oh -
A beacon of light surrounds Wrathion. He rises and speaks in a different tone...
Wrathion says: WE HAVE FALLEN. WE MUST REBUILD THE FINAL TITAN. DO NOT FORGET.
The light fades as Wrathion falls to the floor.
Anduin Wrynn says: What are you trying to pull?
Wrathion says: It is gone. I don't remember any of it. Oh! None of them remembered. The irony!
Anduin Wrynn says: What are you talking about? I don't trust you.
Wrathion says: You are wise not to.
Wrathion says: Champion, I need time to..."digest" what I have learned. But soon, we will take action.