The Underground cavern
1. The enormous underground area is hidden behind a magic and secret passage. It has been located on the rear of the Diad Fortress, to the north west of the village.
2. An underground Lake (has been added? Sorry - my Japanese is very very bad... and my Korean is worse)
3. A teleportation NPC will exist inside Diad fortress. When the fortress is occupied by a Blood Pledge, the gates will be open and it will be possible to use the teleportation facilities. When the fortress is occupied by the Lastabad Forces, the gates will be closed and the teleporter will be unavaialble. Instead, you can collect scroll fragments and assemble them to teleport to the Diad Area and Underground Cavern.
4. Two alchemy teachers reside in the underground cavern.
1) Alchemy teacher of (resistant?) area - The production of (resistant?) village return scroll, physical reconditioning medicine and high-class physical reconditioning medicine. It is located in the (resistant?) regional village.
2) Alchemy teacher of retirement area - The production of (retirement?) village return scroll, blurring eve(eva?) portion, and two other things I can't translate... DOH. It is located in the eastern part of the large cavern.
5. Strong guardians appear in the ruins of the ancient giant and an NPC which produces "the stone of the alchemy teacher" can be found at the grave of the ancient giant which is located in the south east.
In addition, there is a passage which leads to "the sanctuary of demons".
Please note that this information does not constitute any form of announcement from NCsoft Austin, and has been translated from other sites. Please allow room for errors in our translations. Special thanks to JP LineageLatest

"1. The enormous underground
"1. The enormous underground area is hidden behind a magic and secret passage. It has been located on the rear of the Diad Fortress, to the north west of the village."
Another area we won't be able to see, since our server is to weak to take the castle. :(
Two additional things to note
Two additional things to note:
1. The area does NOT require ownership of the castle
2. Diad Fortress will be significantly weakend at this update.
WOOOOOOOOT!!!! That's ver
WOOOOOOOOT!!!!
That's very cool. So it's being weakened, is this because the servers over there are having trouble taking the castle too? or just to make it easier to siege.?
It's related to other parts o
It's related to other parts of the update.
The ownership of diad castle alters many variables in the game - such as the spawn overhead - the lastabads fleeing back through the tunnels, teleporting etc.