I'd love the ability to have a text box that when filled, has a small description of the specific den tabs! Something a user can take advantage of either to make notes for themselves, or to use for lore or any other creative reasons. I'm thinking it ought to have a character limit, just to keep things from getting too verbose, but otherwise having the ability to use html for bold, italics, etc.
Less imminently desired but in the same vein, having the opportunity to have a banner or choose an icon (maybe from site item images?) to select to “represent” the wolves in that den would be quite cute!
