Originally Posted by ArmouredHedgehog
I think "us" just refers to the imps and the hordes of the bloodwar under the nautiloid. They later get boarded by followers of Zariel.
In my absolute speculation thread
sharp commented that it could be an elder brain, namely


I agree that the goblins turning hostile does not appear to make sense.

For some reason a big chunk of EA's narrative conclusions whether its dialogue or events ends up being the same thing or damn near close. Its like the writers have decided this predetermined outcome and although we could twist and wriggle a little we always end up where they want eventually.