A new ruins was added to World of Warcraft: Mists of Pandaria Patch 5.1 currenly on PTR servers. The ruins were added in build 16309 (Nov 14), or the previous one (considering two patches were deployed in less than 36 hours).
The Ruins of Korune is possibly the location where Alliance players will find the Divine Bell during the Operation: Shieldwall Achievement questline. It’s not official this is the location. The interior is currently empty with no NPCs.
The underground fortress shares the same model as the Tomb of Conquerors in the Valley of Emperors (Kun-Lai Summit). There is a big different, however, between the two. The Ruins of Korune has a lot of tiles on the ground that trigger traps. There is no way to players to avoid the traps. The fire traps debuff players with a damage-over-time fire ability. It can be survived if you are a healer. The one that can kill you instantly is the lightning traps. The water traps toss you into the air, which is equally dangerous as it can toss you into adjacent traps.
Many thanks to “Scarty@Anasterian-US” for the heads up while we were playing in-game.