One of the more interesting concepts in Aion are the Rifts. These portals allow for limited PvP in zones outside of the Abyss. Over the last couple days I've had a chance to play with them. They provide a bit of spice to an otherwise bland PvE experience.
A Rift is a unidirectional portal to an opposing factions zone. So once it opens for your faction, only you may enter it. You won't see the enemies coming through it. They appear and disappear about every two hours, so their duration is not very long. You'll often see a message in your chat log like: "A rift connected to Asmodae has appeared.
Not all of the zones in Aion have Rifts. The ones that do are: Morheim, Beluslan, Eltnen and Interdiktah. The rest of the zones are PvE only. The Abyss, of course, is a PvP zone.
The above map shows the rift spawning locations for Morheim while the one below shows Eltnen. They will appear at one of the listed locations randomly. This is a very nice idea, as it prevents camping of the portal site. On the downside, the locations of your portals can be difficult to find.
The portals are similar to the wormholes of Eve. They only allow a certain number of players through them before they collapse. This number is small ( 20 or less) and can vary between rifts. It should prevent any massive incursions. It also means you can easily get cut off from your group.
If you perish while in your enemies territory, you will respawn at your bind point unless you are resurrected. Some enterprising raiders may choose to bring a mobile kisk in order to have a longer stay. These mobile bind points allow you to rez anywhere you place it. They can be destroyed and expire eventually, so they won't allow for a permanent stay.
So why use a rift? To harass those pretty boy Elyos is usually a good enough reason. You will gain Abyss Points from any player kills too. There are also a number of quests you can do in your opposing factions territory. They are often labeled with the SPY tag.
Rifts are a great diversion during your push to the Abyss. While they add some excitement to the PvE gameplay , the controls (duration, randomness, limits) prevent them from being too disruptive.
The maps were found here.