You know who would be the ideal candidate for a small scope gameplay update?
Karthus.
No seriously, I'm not joking here. I remember the times before he got his VU, and now he looks slightly better, but sadly his gameplay has not improved a bit since then, if anything Riot decided to nerf his W, the only utility he had, into the dumpster and indirectly nerfed his ult by releasing more and more champions that could either make themselves invulnerable, or make the team invulnerable (f.ex.: Bard, Kindred, Taric), or introduced an item with an on-demand spellshield active.
He has no real burst and no cc either, which is usually what allowed mages to compete with assassins. A Zed can be 20/0, he still is in some big trouble when he gets hit by a Morgana Q, Lux Q, Veigar cage or a Brand stun. Also this cc allows mages to be still semi relevant even if they are horribly behind, as a well placed stun can turn a fight or make a good pick.
But Karthus can't do that, as he consists of mostly damage and is maybe a living slow zone when you buy a 
- which is a shame because his theme had so much more potential.
He definetly needs something, and yet his kit is completly lacking of anything worth keeping in its current iteration. Sure the ultimate should still be this gigantic "deals damage to everyone" thing, but even this could be done better.
