Experimental Thornmail Change on PBE Was Promising

"I was spiking out a concept for an item that you can buy to ensure you aren't just a lifesteal battery for enemy carries; Grievous Wounds was the easiest quick-and-dirty implementation that would give good learnings. Still interested in some version of this direction. This precise list isn't going to work for a couple of reasons, so no promises. " - RiotAxes

This has been something I've thought would be a good idea for a while. Nothing as a tank sucks more than feeling like you're wasting your gold and effort trying to lock down (insert Draven, Vayne or other late game carry as you see fit) and being melted in 3-4 seconds, with any damage you might put out just healing right up. I'd like to see some variation of this change happen, and Thornmail is probably a better place for it than a whole new item.