The dungeon friend screen is used to set a list of people who are NOTÂ allowed access to a dungeon or room.
This screen can be accessed either via the friend button found at the bottom of the screen when inside a dungeon room.
The list will show everyone who is either inside the current room or on the world tile outside you can select a person on the list and it will automatically add them to a list of people not allowed to enter this room and turn their name red to indicate it worked.