Let's give Dr. Mundo a new passive

Dr. Mundo's passive is easily the worst case of "invisible power, no gameplay" in the game. While other Champions like etc. might not have particularly interesting passives, Dr. Mundo's is by far the most egregious. Bonus health regen based on his maximum health is hard to appreciate, not exciting at all, and contributes very little to Mundo's overall power; if he really wants to regen fast, he either uses his ultimate or takes advantage of .

So let's see about giving him something new, yes? Let's not wait for a VGU, which would probably take another 2 years or more.

One idea I had for a new Mundo passive would be something like this:

"Each basic attack or Infected Cleaver hit against an enemy Champion adds a stack. Upon reaching X stacks, the stacks are consumed and the target receives Grievous Wounds for Y seconds."

This fits Mundo's sadism/pain theme, and helps carve out more of a unique "trade superiority" niche for him without requiring him to rely on health regen (something Garen does better in any event). By letting him have built-in Grievous Wounds, he becomes able to cripple an enemy's healing, but the fact that it requires him to build up stacks on an enemy allows them the chance to react to it (certainly more than against item-based GW).

But if this would be inappropriate, what do you think could be a good alternative?