It's just stupid that you can't join back to Prison of Elders if you for example get disconnected from the match after 4th wave... You and your teammates just have to redo the whole bullshit from the beginning... At least on higher difficulties.
I hope that the creators could for example make it so that if you get disconnected from the match you could join back into it for 3-5 minutes after the disconnection.
-
You have to join after they wipe.