@Riot, Karthus badly needs changes (Some suggestions included)

Karthus has been in a rather bad spot for a while, and it's getting worse.

Currently, Karthus is being driven out of lanes in an extremely harsh manner. Though some old champs are being nightmares for him already, with each new champion since Zed except for Zyra and Vel'koz his overall usefulness on a team is being cut down.

He can't lane against Yasuo, Zed, Fizz, or Ekko. Ever. Each one of these four champions, is a utter nightmare for a Karthus player. Yas can use Karth's minions to dodge Karth's main source of damage with ease. Ekko is.. Ekko. By the time Karthus hears Ekko's echo, he's already deader than dead. Fizz can simply troll pole onto Karthus, killing him without giving Karthus a chance to do anything. And Zed can just shadowport around Karth and laugh at his attempts at hitting him.

Talon is an awful experience for a Karthus, but nowhere as bad as the previously mentioned four. Karthus can deal with a Talon by playing safe, but he can't deal with the previous four even if he just hugs turret and farms. Once they reach 6, they can dive and kill him with no worries at all.

Other new champions, like Bard and Tahm, are completely screwing him over in another way. Though Bard to a much lesser extent, as his ultimate can potentially screw over anyone if used right. But Tahm can simply eat anyone low enough to be finished by Karthus' ultimate, and it's a free zhonya's for them.

Tahm devour does not block the damage from things like Zed ultimate, as I've had allies die in my stomach to it while playing Tahm. However, Karthus ult IS blocked by Tahm devour which is the start of the grief of Karthus players

Like Tahm's devour, a growing number of champions have an untargetability mechanic that can prevent Karthus ult from ever doing damage.

Master Yi, Fizz, Vladimir, Maokai, all have abilities which nullify Karthus ultimate when properly timed. The problem here, is that the cost that they have for using these abilities in comparison. Out of the four of these, Vladimir is the least Karthus breaking. Because he has the longest cooldown of the four.

Ekko, Zed (Yes ,Zed ult can make you immune to Karth ult if timed right), Bard, and Shaco are actually fine completely fine when it comes to the topic of immunity to Karthus ultimate. Why? Because they use their ultimates to counteract his. It's a ult for ult trade. But Karthus still has a major disadvantage when it comes to ultimate for ultimate trades.

The big disadvantage is his extremely long ultimate cool down. Every time he gets his ult, these champions will have their ults cooled down once or twice while Karthus ult cools down. And they can exploit it to take no damage from Karthus ult, ever.

Itemization is also butchering Karthus. One Locket of the Iron Solari, will ruin his ult. And yet again, it's another item with a shorter cooldown than Karthus ultimate with max CDR at lvl 3 ultimate. Maw of Malmortious, Banshee's Veil, Guardian Angel, Zhonya's, all also ruin his ult easily. Guardian Angel honestly has the least effect on his ult, as it's an item with a longer cooldown than Karthus ult.

For starters, I would suggest changing his W (Wall of Pain), give it some sort of utility that would make it actually painful. Certain champions don't even care when they go through it, as they're too fast for Karthus to hit. They have slow removals, Quick Silver/Merc Scimitar, or the occasional support with Mikael's.

As an example, make it stop dashes. It would evolve from being the less-than-satisfactory thing that's only really useful for reducing tankiness in tanks. It would grant Karthus the ability to escape from several high mobility champions if properly used. Though some champions would still brutally bully him, he would cease to be free kills for certain champions.

Or, change his ultimate. Lower the early-mid cooldown by a chunk, or increase its AP scaling by a bit. It should either do more damage, pierce through those pesky untargetables, or be able to be used more often.

Reduce the amount of CD for interrupted channel to 50% or give it something like: CD is reduced by 10% per champion it kills.

The number of champions who can easily interrupt it, is the majority of the champion roster.