This is mostly a compilation of other people's work, which I have made small edits to to fit my own purposes/liking. I don't take credit for other's work.
This is my attempt at recreating my Kui Nameplates from legion, with color changing based on MotC Missing/Applied, unfortunately this does not seem to be a feature available in Kui anymore.
I've also got it setup to change color when mobs are targeting a druid's Treants, or a monk statue. This color is set to purple, but could be changed.
(This is only active in Tank Spec.)
I have the colors for MotC Tracking Set to
Purple - Without
Green - With
(This is only active in Windwalker)
(this could be adapted to other classes dots relatively easily)
This has MANUAL Buff tracking enabled. I've only got debuffs that I need on the 4 classes that I play enabled.
(Windwalker/Brewmaster Monk, Vengeance Demon Hunter, Balance Druid, Marksmanship/Survival Hunter)
It would need other debuffs to be added manually for other specs, or change to automatic buff tracking in the settings.
This is a relatively straightforward procedure, I just do not have the need to add more at this time, and do not like the clutter of unnecessary debuffs on nameplates.
Perhaps this is what someone else may be looking for, or could be used as a jumping off point, or even just used to get the mods I have enabled on this profile, and completely change everything else.
I'm uploading it mostly for me as a backup.