How do I enter the Verdant Chambers castle?

[Seems]

So my 7th level monk visited the Guardian of the Bloom on his own and escaped without significant damage. I rustled up my party and headed back for some revenge, and took out all the guardians. However, when I attempt to go inside, I'm confronted with an undetectable negative levels trap that hits for anywhere from -2 to -13 levels (which killed Linzi), and I'm unable to open/pick the lock on the door. Without too many spoilers, I assume we'll gain the ability to enter some time later on in the adventure?

[HTakara]

it's for later, come back when you're higher level

[A-94L542 Abyssal Admiral Lavelle]

You will have to go here as part of the main mission of a later chapter

[Seems]

Thanks!