I haven't played the last parts of Legion, but I have watched all the cinematics.
In the last cinematic, Sargeras is pulled from Azeroth by the other titans, and then he stabs the planet.
But how did he end up there in the first place is not explained in the cinematics. I know that Illidan made Argus appear next to Azeroth, but there was no sign of Sargeras.
Can someone explain?