Aion's forthcoming Assault on Balaurea expansion? You're in luck, as today finds the new content live on the Public Test Server, a couple weeks ahead of its September 7th release date. Pre-existing PTS players will find that their characters have been wiped, which is a small price to pay for the chance to test the new content with accelerated XP and loot drop rates.
Assault on Balaurea features a new pet system as well as new zones, instances, quests, and a level cap increase. Check out the official press release for more information, including how to install and run the PTS client.