Karthus has become one of the premier mid, jungle, and bot lane picks in patch 10.14. Thanks to the steady jungle experience buffs and the reversion of some ill-advised nerfs to the champion, this hyper-scaling mage has risen from the ashes.
Karthus was one of the hardest hit champions after the preseason 10 jungle experience nerfs. By reducing jungle experience and decreasing neutral monster spawn timers, Riot effectively nerfed the champion into the ground.
Karthus does not provide as much utility, and is not as safe in the mid lane, as other popular mages. The champion also received some major nerfs to its base damage and AP ratios early in season nine and that cratered its pick rate in the lane.
Karthus jungle rebounded on patch 10.3 when the jungle experience nerfs were toned back. This brought his pick rate back up, but it steadily went back down until it dropped off a cliff on patch 10.9.
In that patch, Riot reduced the champion’s movement speed by 10 and effectively stopped players from picking it. The change reduced Karthus’ pick rate in the jungle and, inadvertently, in the mid lane. Karthus players could no longer dodge enemy skillshots effectively in the lane because of the nerfs.
Riot would revert those changes and tweak the champion a bit more on patch 10.14. The balance team increased his health, improved Lay Waste while reducing its damage to neutral monsters, and also gave a slight buff to Defile. By trying to balance the champion for the jungle without taking away his agency in the mid lane, Riot buffed Lay Waste to the point that it is oppressive at all ranks.
Karthus was never a premier bot lane pick. He needed too much gold and experience to be played optimally alongside a support. But the recent buffs have changed that entirely. He has become a lane bully in the bot lane. Karthus, paired with an engage support, is now a deadly combination.
Now, Karthus is one of the top 20 most banned champions in solo queue. This, plus his current win rates in jungle, mid, and bot, should put him on the short list to be nerfed in the upcoming patches. Players should expect some changes to Lay Waste, probably reducing its damage to neutral monsters even more while aso nerfing its base damage.