This happens when trying to do the rubble collection event after an assault to rebuild the walls. If there are not enough people doing the event, it fails and often, those giant vine things that pulse poison will spawn. Though, if you are standing directly on their spawn this happens:
http://i.imgur.com/Frloejk.jpg
http://i.imgur.com/Frloejk.jpg
http://i.imgur.com/yx8CFhe.jpg
I got stuck inside of the vine, and died, you can’t waypoint out, and as a necromancer I have no teleports.
