What is this?!?!?!?!?

[Babykoala (Sarah)]

What is glintstone - jadis' secret lab????
We found this place while doing elite forgotten citadel we started in a complete black/off the map place and u have to walk straight for about 10 sec and you reach a lab
Can someone tell me where this is or what it is?

[Kakashis]

It's for completing the banished set