Malzahar

I'm a bit lost for words at the moment. Why is Malzahar getting SO many nerfs? Over the past FOUR patches where Malzahar was involved in, it all involves Damage reductions, AP scaling reductions, CD increases etc. When I started ranked competitively, I got adviced to train Malzahar, but this guy didn't even have an idea yet how bad he has become independently, as he used him last somewhere early season 7.

He used to be a good counter against Veigar, but right now even Veigar easily beats him. His power independently (Void Swarm, Malific Visions + Nether Grasp) Is not strong or valiable enough to actually kill anymore, so his laning power has decreased. Why is this midlane champ being bullied so badly while other midlaners still dominate so much? (I'm looking at you, Katarina.)