I decided to spec Coriel as Protection/Retribution, to see if Improved Retribution Aura did anything. On my way to Imp Ret Aura, I picked up Vindication. I knew it wouldn't work on raid bosses, but I figured it might be a handy talent for 5-man instance tanking, and that I could always respec at 70.
This was a mistake.
Vindication does not work on raid bosses, 5-man bosses, or random instance trash mobs. Heck, at this point, I'm surprised if it does work on a mob.
Honestly, why even have this talent if it's not going to work on anything? If it's overpowered, scale it down, or remove it and replace it with something useful. Right now it's just a complete waste of talent points.
The worst part is that you can't even guess what Vindication will affect. It seems almost random.