A "Grim Gate" allows progress to the next floor when a Fiendish ID Card is used on it.
Notes
A place to gear up.
As the Fiendish Memo from Morgral'm can be read by interacting with screens in front of the Grim Gate. A member of the party needs to use a Fiendish ID Card in order to access the next floor. To "use" the ID card, simply have one in your arsenal, and interact with the portal in the middle of the Grim Gate. Doing so will remove the chains, consume the ID card, and lock the party, similar to how using a Shadow Key works. The squad can proceed to the next floor once everyone is standing on the pad.