Ok so i was going ghost avalon for the first time with some friends. We made it up to young morganthe, but i died, and my other teamates said they didnt have heals in . So i fled and came back to the entrance. I told the people around the entrance not join, but at the LAST SECOND, some guy joined on PURPOSE and made me lose all my progress . KI you need to put some type of request that asks the person if they want someone to join!
Personally I think there should be a way KI can place your wizard back where it was in these instances no matter who joins on the pad for spite, it is a chronic problem that happens often. Your wizard should not be effected especially in these fights that require a lot of your time and help to complete. Let your wizard be in the original instance and the other wizard theirs.
Lets face it how many are going to be willing to complete an instance with a claim jumper like this. I have had it happen to me and I have just turned around and exited out of the instance with hopes I have find someone to help me with it another day.
. So i fled and came back to the entrance. I told the people around the entrance not join, but at the LAST SECOND, some guy joined on PURPOSE and made me lose all my progress 
. KI you need to put some type of request that asks the person if they want someone to join!