Instead, we fight some shallow placeholder boss, and then all we get is a cinematic of Sargeras being imprisoned. Sargeras has been the big bad guy for so long, they've been building up to a battle with him for ages. And then they don't? We fight Archimonde, we fight Kil'jaeden, but not Sargeras?
How did they even imprison him? How the hell did the Pantheon even revive? They were all killed off by Sargeras and their spirits lost. Aman'Thul was aborbed by Lei Shen and should have died with him.
It's just fucking stupid that Sargeras, at full power, can be imprisoned by the Pantheon who he already killed once that revived out of nowhere. They should have at least let us battle him. We're probably never gonna see the Legion in the spotlight again, and this is the way they concluded it? Bullshit.