Pyramidal Dome 

Minos gestured a few times and created one last seal on two similar artifacts. 

He then handed one to Ruth and the other to the level 85 Spiritual Sage. "This is the joint key to this dome. By using both parts of it simultaneously, you can open the city to visitors.

Without one part, the other cannot do the same, so one of you will stay outside the Dry City, and the other will stay inside, controlling the entrance of people."

The two received those items, looking at what looked like a medallion, but had a large pyramidal symbol on them.

"How do we arrange to use this simultaneously?" Ruth asked. 

"That defensive barrier does not prevent the transmission and receipt of information. You can still use communication arrays inside this place as you did before." Minos said, teaching these people. It didn't do much harm to the lives of those inside this place.