The forgotten Karthus

After the update on assassins, I feel like Karthus (and not only) needs a strong buff. It is unfair that Karthus players are trying hard to do something in a game, while, for example LeBlanc/Katarina/Talon players can win with very little skill. In addition, the buff on support items plus the new Redemption will totally negate his ultimate, which for some reason still costs 120 mana and has 3 minutes cooldown.