Bro no lol, just chill.
It will be your standard xpac like any other involving Burning Legion, bad guys try to summon Sargeras in Azeroth, we close the portal(s) right in time, and that's it, the world is saved once again, and Burning Legion is delayed.
It's still too early to bring the final big boss out, even the thought of us fighting him is ridiculous.
It might be Kil Jaeden tho, since the xpac is called Legion, they must bring someone out who's pretty high in their ranks, and even he should be pretty OP for us.