Someone posted this on the normal forum, but as it got deleted I'll post it here as well :
1. Make a friend and enter a rated arena 2v2 pvp match
2. Not sure if needed, but I always wait for the fight to start
3. Type : /leave
You will get like 40 silver and a reward box by doing that. That reward box can contain AMP and Ability point stuff (same as the elder gem vendor ones), trigger fingers and other stuff I can't remember right now.