Simple exploit that some might find useful, especially on pvp server.
1. Queue for proving grounds
2. Go anywhere
3. Escape to proving grounds by teleporting to the dungeon.*
4.(Optional) use [Treessassin's *****]/class abilities to remove yourself from combat to be able to teleport.
5. Profit!
*It will kick you from the dungeon after some time. Didn't count but probably after around 10 minutes. Seems to be extending each time you teleport there.
Enjoy while it lasts.