Invisible for a User / Ghost Mode

Invisible mode is great on Discord (Great Job Devs) and it's a surprise that more platforms have still not adapted this. It would be awesome to go one step further and add an “Invisible for a User” option or a “Ghost Mode”. You could have the person that is “ghosted” show up at the top of the friend list for visibility and maybe a special spectral color or animation surrounding their name. At the very least an icon next to their name as a reminder. Also, further down the line you can group friends into categories and “ghost” the group.