Potential changes to masteries
Scarlet Steel was a lore referenced item that cut the heal effects of enemies. The item never made it into the game, but it could be introduced as a utility option in the mastery tree. Somewhere in the trees we could put in a mastery called Scarlet Steel which acts as grievous wounds. With the lack of items carrying this ability, and its very powerful nature, it could be buried deep in the tree.
Scarlet Steel: Req. 19 points (?) Mastery Max lv 1 Dealing damage to units below 40% health will apply Grievous Wounds. Grievous Wounds reduces healing effects on this unit by 50%.
There is currently only one item in the game with Grievous Wounds and that item is Morellonomicon, which without Grievous Wounds is still a very powerful item. I see no issues introducing Scarlet Steel into the mastery tree.