Karthus can cast spells for a short duration after he is killed. Move away from his corpse to be safe.
Make sure you always have enough health to survive Requiem, even if you have to go back to the base more frequently to heal.
The stat comparisons provided here show some important Yuumi against Karthus counter statistics that may help you grasp the differences between the pair. For instance, Yuumi’s KDA ratio ([kills + assists] / deaths) of NaN is greater than Karthus’s ratio of NaN, demonstrating that Yuumi may be more central to her team's team fighting potential than Karthus. This observation is largely caused by the differences in assists.
Yuumi often has a significantly smaller longest kill spree than her matchup does. On average, she receives less damage than Karthus. This is usually reflective of differing health capacities, yet it can also imply that the one champ has less agility and thus is unable to kite away from additional damage when poked or engaged.
Both League of Legends champions are great. Both have their strengths, weaknesses, and counters. In League's current meta, Yuumi usually fairs equally well when playing against Karthus, with a 49.6% win rate. Therefore, Yuumi makes an ok counter to Karthus.
While Yuumi does have a lower winrate compared to Karthus, when they face off with one another, Yuumi also has a much lower difficulty level that makes her a less time consuming champion to pick up and master. You should be careful when picking Yuumi into Karthus.
Moreover, Yuumi has a very large amount of utility and CC, a similar amount to Karthus. This often makes her just as valuable during team fights, especially when trying to counter champions with a lot of burst damage.
While there isn't a single best champion in League of Legends, in Yuumi vs Karthus matchups, Karthus is the better champion with a similar win rate, less champion complexity, and a similar amount of utility to help out your allied champions during late stage team fights.
Yuumi is a somewhat poor counter to Karthus. Make sure you focus your play on maximizing your gold income and taking out objectives. If you can do that, you should be able to stand on your own as Yuumi against Karthus.
To learn all of the intricacies of Yuumi to counter Karthus during both the early game and mid / late game phases of League of Legends, you should continue reading to gather a few extra lessons on this matchup. If you pay attention to the build and suggestions shown here, you should increase your win rate by a lot and be closer to League of Legends pro players.
Yuumi typically racks up a lot less CS as Karthus. Champions who on average don't get much CS typically don't require much CS to be valuable teammates, such as sup champs. These kinds of champions are capable of scaling properly off of their skills, stats, and first items alone. Yet, champions with a lot of CS, such as hyper-carries, typically have to have several high cost items to be effective. In either situation, try to do better than the values shown here to do well.
The best items to use in your Yuumi versus Karthus build include Ardent Censer, Dream Maker, and Staff of Flowing Water. When Yuumi used at least these three pieces in her build, she performed significantly better against Karthus than with most other common counter builds. In fact, Yuumi boasted an average winrate of 49.6% when playing against Karthus with this counter build.
To have the highest chance of beating Karthus as Yuumi, Yuumi players should use the Summon Aery, Manaflow Band, Transcendence, Scorch, Font of Life, and Revitalize runes from the Sorcery and Resolve rune sets. Out of all the rune builds that we analyzed for Yuumi vs Karthus face-offs, this composite of runes resulted in the best win rate. Notably, these runes averaged a 49.6% win rate overall.
By default, tips, stats, and builds on how to beat Karthus as Yuumi are displayed for all ranked divisions combined. If you want to scope the stats and builds to an individual division, you can use the selection menu earlier in the counter matchup guide.