Lay Waste is very strong at farming minions and harassing enemy champions.
Ask your allies to help point out when you should use Requiem to get kills in different lanes.
The Yuumi Karthus synergy stats shown here demonstrate the areas of her gameplay that do better (or worse) when paired with Karthus, compared to her overall stats. Significant differences are areas of focus that highlight how her gameplay changes when paired with this other champion.
Overall, Yuumi sees a large worsening in her KDA (ratio of kills and assists to deaths) when paired with Karthus. His KDA decreased from NaN to NaN. This fall shows that Karthus helps Yuumi perform worse in ranked League games. Yet, the small difference proves that this performance change is not very impactful.
When Yuumi is paired with Karthus, she observes a marginal improvement in her complete damage dealt. This may indicate that Karthus supports by providing cover for her to dish out more damage or that his presence on the team also helps extend the round's duration. Similarly, when Yuumi is played together with Karthus on the same team, he usually scores many fewer killing sprees compared to when she plays on his own. This is contrasting evidence that she is worse when playing with Karthus.
Moreover, when Yuumi plays with Karthus on the same side, she usually receives much more damage than when she plays alone. Receiving more damage could indicate that Karthus does a poor job of covering Yuumi during teamfights.
There is no ideal champion pairing for Yuumi that will always be her ideal teammate. However, overall, Karthus is a terrible companion for Yuumi. By locking into the same side as Yuumi, he decreases their win rate by -3.8% to 40.1%. This clearly indicates that there is a very bad bond between Yuumi and Karthus that allows them to perform worse together than without each other.
Karthus has a much greater difficulty compared to Yuumi. That means you must be cautious when enlisting Karthus teammates to play with, as they will require a much greater level of skill to be able to play well with you.
Working alongside, you will likely see an overall large increase in your team’s capability to deal magical damage. Together, these champions can deal quite a lot of AP type damage.
In contrast, by grouping Yuumi and Karthus together, you probably will not be granting your side a great deal of engage potential. We recommend you include other champions on your team that neutralizes this relative hole in their potential.
Regardless of the ability of your Karthus teammate, you should focus on maximizing your gold income, warding to avoid ambushes, and clearing objectives. If you follow these simple suggestions, you should do well anyway.
If you would like to truly master Yuumi in order to synergize with Karthus during both the lane and mid / late game phases of LoL games, you should continue reading to pick up some more tricks and insights into this champion pairing. If you listen to the build and suggestions presented here, you should grow your win rate significantly.
The ideal items to focus on in your Yuumi and Karthus synergy build consist of Ardent Censer, Staff of Flowing Water, and Moonstone Renewer. When Yuumi combined at least these three items in her build, she performed a lot better as an ally of Karthus than with many other commonly used builds. In fact, Yuumi boasted an average winrate of 40.1% helping carry Karthus with these items in her kit.
To have the highest probability of vanquishing your oponents, Yuumi players should equip the Summon Aery, Manaflow Band, Transcendence, Scorch, Font of Life, and Revitalize runes from the Sorcery and Resolve rune sets. Of all the rune builds players used for this team composition, this combo of runes resulted in the highest win rate. In fact, these runes provided a 40.1% winrate overall.
By default, tips, stats, and builds on how to synergize Karthus with Yuumi are shown for all skill levels combined. If you want to scope the statistics and builds to a particular player tier, you may use the selection menu located earlier on the page.