“While it is true that the Fel Hammer is powered, sadly, its jump engines are non-functional. If we are going to invade a demon world, we're going to have to make the command center jump-capable.
We need some replacement parts.
Luckily for us, the Legion brought a couple of command centers and soul engines along with them to the Broken Isles. You will find them at Faronaar in Azsuna, and at Felsoul Hold in Suramar.”