Exploits are a pain for gameplay no matter what server you are on, but it can kill PvP play. Check out this one, and if you have any information that can lead to an end of an exploit, then share it! One PvPer, Roald, shares this:

The person is invited before the fight starts, and leaves the invite box up, then accepts when the fight is taking place.

I have experienced quite a few Freeps doing this to me and this definately needs to be fixed.

Aeralik replies with:

I've seen the complaints about this and I've tested it locally. From my local testing it seems to be working just fine. When you click accept if you are hated by anyone it will not add you to the group. The same thing applies if you hate a player. If anyone in the group you are about to join is fighting it will also cancel out. If there is some strange combination I am not seeing then you can pm me with details.

If you have information or insight on this exploit, then please share it on this thread.