Grevious Wounds is Worthless
In a world where Riot took one look at conqueror and said "Oh, the true damage, that's the only problem with this keystone. So let's remove the true damage and then up the healing by about 10 times to 'balance' it out" grievous wound items are becoming and 'every game' item instead of just being built to target sustain tanks like Mundo or Darius or Illaoi or champions like Draven who rush a bloodthirster with Yuumi on his back.
And it has become apparent just how little grievous wounds actually does. A fully stacked conqueror jax with a vamp scepter and a yuumi who is even remotely ahead of the gold curve of the gave is going to be able to 1v3 to 1v5 relatively easily as long as he has mana because he is going to sustain himself effortlessly. And if you're wondering why I bring up yuumi, its because grievous wounds is the only counter to her healing. I can blow up Nami or Soraka or Sona and then turn onto jax. Not so much with her. So the only option I have is to build Morrellos, bramblevest/thornmail, or executioners/mortal reminder.
It doesn't do shit. The number of my recent games where I've seen a champion whose only form of sustain is a passive and the conqueror keystones outfight several carries solo even while ignited with a grievous wound proc is absolutely inexcusable. It's almost every game thanks to Champions like Jax and Mundo doing so well int he current meta and champions like Yuumi being one of the only champions that can survive the early game in this burst-first meta.
Building a grievous wound item is supposed to be a trade-off. Morellos is expensive and offers far less AP, no CDR, and no mana. Executioners and mortal reminder are gold inefficient and provide less armor pen than last whisper and far less AD, no crit and no sustain. Bramble vest and thornmail while being more gold efficient than their counterparts for the ADC and AP role is still a trade-off due to its lack of CDR, low HP, no damage reduction passive (ie, frozen heart, randuins), no CC buff (Gauntlet, mallet, etc) and being a poor tank item early because you need more HP than armor early on (typically, tank items are trash atm but that's another topic for another thread).
Getting grievous wound items hurts your overall damage because it is a counter-pick item. Much like QSS, it's designed to trade off raw damage for an ability to hurt the game-plan of an enemy player. If there weren't a trade-off then certain champions (ie Mundo) just wouldn't be able to be played at all because people would just easily slide a grievous wound item into their normal build. But because there is a trade-off the item passive needs to actually fucking work. Currently carries and teams in general are in a lose-lose situation. Don't build these items and lose because the enemy outheals you, or build these items and lose because the enemy outheals you and you have less damage than you should.
My solution? Increase the heal nullification effect on this passive by about 10% and see what happens. In the current meta of sustain-bruisers and fighters being tankier than 900 armor malphites because reasons it may not even be enough but I think it will be a good place to start.