Grievous wounds simply don't work as a concept

This mechanic should not exist in this game, especially when it is accessible to mages on one of their core items.

It makes balance impossible, where a champion is either overtuned on heals and regens without GW and balanced when hit by GW or balanced without GW and underpowered when hit by GW. There is no between and given how ubiquitous Morellonomicon is, Grievous Wounds will never be balanced. At least ADC's have to make a choice between taking Grievous Wounds or Doing more damage.

To fix this, one of these must happen: ->Grievous Wounds are removed - all heals are now balanced around its absence

->Grievous Wounds only apply to Lifesteal - really the sole reason why Grievous Wounds still exist is because of Lifesteal

->Grievous Wounds are more gradient - the lower health you have, the less you heal. Gets rid of the arbitrary limit of 40% (AP) or 100% while being attacked (AD) and makes more thematic sense. Still will make healing unbalanced in the the long run.

Riot made a big uproar about how a single item (QSS) countered some things like Zed's ult and that he had to be overtuned to compensate, this is an entire status effect that conditions too many champion's kits, i.e. Soraka. Mundo downright can't function because of this. At least TRY to be consistent in what you say and what you do.