Karthas jungle should be Riots priority to delete right now.
#1 He is the highest win rate jungler in the game. #2 Jungle Karthas is the most un-interactive gameplay LoL has EVER seen, and it is rewarded by being the best pick possible. In all circumstances. #3 There is absolutely zero skill expression in it. You don't even need to have arms. As long as you clear your jungle with your face, and press R with your foot every once in a while, you are going to outperform the enemy jungler. By a significant margin.
This really should not be a thing, My proposed fix: give his ult a damage based on distance effect. (Idk the exact numbers of his ult, but this is an example) Requiem of the Dead: Deals 250-500 damage to all enemies, closer enemies take more damage, farther enemies take less.
OR
Make it only do full damage when he's dead, and in his passive.