The Chaos Rift in Raiyan Cave.
The Chaos Rifts are mysterious dark portals appearing during the Dragon Festival 2006. The first Rift is found in Raiyan Cave on Panjiang Peninsula during the Darkness at Kaitan quest, and spawned the foul Lesser Grasps which drove the Naga dwelling in the cave from their home.
The Rift can be targeted using the mouse, but does not respond to clicking. The Rift resembles the dark portal that appeared in the Tomb of the Primeval Kings on Tyria which is responsible for the infestation of dark creatures that plague the tombs. The Lesser Grasps spawned by the Rift in Raiyan Cave are weaker versions of the Grasps of Insanity found in the tombs.
The rifts also play a central part in Haiju Lagoon (mission) and Jaya Bluffs (mission) as targets to be destroyed. These are missions given by Captain Rujiyo during the Dragon Festival 2006. More Chaos Rifts, named only Ruptures, have appeared on Elona.
One of the screenshots of Canthan New Year 2007 also has a Chaos Rift in the background.
Chaos Rift in Lion's Arch
Chaos Rifts also appear during the quest Sunspears in Kryta where you must travel through Lion's Arch and get rid of them. Similarly, they also appear in Kaineng Center in the quest Sunspears in Cantha where you must defend Kaineng Center against certain doom.
They are also present in the missions Dzagonur Bastion, Grand Court of Sebelkeh, and Gate of Madness, and they are also in the challenge mission Shadow Nexus.