The Nerf-hammer and who deserves it

Riot games is a great company and works hard to keep the game entertaining, fast paced, and fair. Although this is all true, i have yet to see a nerf for some of the champions i think deserve them. Im not saying my opinion is correct or all of these champions are "overpowered" but some of them need tweaking and are extremely powerful compared to other.

My mentality when it comes to nerf-worthy champions and "op" champions are extremely survivable cha mpions that deal immense amounts of damage. There are many exceptions like nasus, jax, and olaf who are not overpowered and fill that category just right. However, there are others like volibear, and vi who seem to take next to no damage and deal immense amounts of it while supplying their team with great crowd control and an even greater front line. Champions like lee sin, who have great early games and seem to somewhat fall off lategame are also very strong and require little amounts of tweaking.

Nasus, Jax and Olaf require little to no tweaking even though they fill the role of "tanky damage dealer." Nasus requires immense farming and time to get going strong enough to carry and jax is very item dependent. Olaf has a large array of champions that can counter him. However, Volibear is nearly invincible unless focused extremely early by jungler for about a couple minutes. He does insane amounts of damage by building straight health because of his (w) skill which scales well of off health. Rather than nerfing him immensely, i feel a slight ratio change on his w would work wonders. Vi is not necessarily overpowered now that her ultimate no longer makes her immune to cc. Although, I commonly see myself being 100-0'd by VIs who have nothing but a spirit item and a phage. I reckon a very slight nerf to her q or e ratio would do the trick but i feel as if riot is worried she would be nerfed to oblivion.

On a latter note, Evelynn received a major "buff" that accompanied the vision changes in season 4. All of season 3 it felt as if pink wards were your best friend against an eve jungle. Since they're permanently visible this season, she is substantially harder to be ready for as she can just destroy pinks any time she is near a lane. I have thought of having jungler presence near wards or defending them as a means of preventing any ganks by her, but that would force junglers to spend less time ganking other lanes or farming neutrals and more time following an invisible champion around trying to guess where she could be de-warding next. I would recommend a ward type that could see invisible CHAMPIONS only. This wouldn't necessarily nerf evelynn's map presence as this ward could be priced around the same as a pink ward, and used to prevent jungle ganks while pinks could still be used to prevent enemy vision. Thank you for reading through all of this and feel free to respond your thoughts, constructive criticism, any ideas that would better mine, etc.