Can we buff grievous wounds?

Grievous wounds is suppose to reduce healing right? but against who?

iv had to many games where someone builds or and then totally becomes unkillable you can even apply grievous wounds to them but because they are dealing so much damage its pretty useless so whats the point if say draven builds a BT and because his Q hits like a truck he stil lgets back more health than people can deal damage to him even with a good chunk of healing reduction