I've gone into the master's tower a number of times now. And what I've seen happening is that sometimes it puts everyone that's on the entrance sigils all into the tower together, and sometimes it does.
I've gone in with parties of three, parties of for, parties of two, and solo.
sometimes, regardless of the number of people on the sigils during the countdown, we all wind up in a tower by ourselves.
Sometimes we all wind up in the tower together.
Sometimes only two of us wind up in the tower together and who knows where the others went.
I like these towers here in Ravenwood and I'd love to see them stick around after the event is over, but I think that they have a few bugs that do need to be fixed.
if there are people on the sigil that were defeated, fled, or teleported from the tower, they are reentering the instance they last left the tower from as if it were a dungeon.