This is a very simple Target of Target frame, which is positioned underneath the default target frame. The window will show the name of your target's target, their life bar, as well as up to 6 debuffs. The target casting bar will be positioned below the Target of Target bar, if you have it enabled.
The mod also adds a simple AGGRO message if you pull agro to both the combat log and the combat errors message frame.
Currently there are no options, the mod is just as is, but I plan to add the ability to toggle the extra features on/off soon.