Kassadin's ultimate has many uses and is on a shorter cooldown than most, use it often.
Kassadin has multiple item paths; he can go caster via Mana and Ability Power or anti-caster with Cooldown Reduction and Magic Resist.
Try to get the Ancient Golem buff to counteract Riftwalk's increasing Mana cost.
The Kassadin Yuumi synergy stats shown here demonstrate the areas of his gameplay that do better (or worse) when paired with Yuumi, compared to his overall stats. Significant differences are areas of focus that highlight how his gameplay changes when paired with this other champion.
Overall, Kassadin sees a very large drop in his KDA (ratio of kills and assists to deaths) when paired with Yuumi. His KDA decreased from NaN to NaN. This drop shows that Yuumi helps Kassadin perform worse in ranked LoL matches. Yet, the small difference demonstrates that this performance change is only marginal.
When Kassadin tries to synergize with Yuumi, he gets a noticable drop in his full damage output. This change may indicate that Yuumi does not support by providing cover for him to dish out more damage or that her presence also helps extend the round's duration. Similarly, when Kassadin is played with Yuumi on the same side, he usually scores many fewer killing sprees than when he plays without Yuumi. This is contrasting evidence that he is worse when playing alongside Yuumi.
Additionally, when Kassadin plays with Yuumi on the same side, he typically takes less damage than when he fights alone. Getting dealt not as much damage may mean that Yuumi does a decent job of covering Kassadin during teamfights.
There is no one best companion for Kassadin that will always be his ideal synergy. Yet, overall, Yuumi is a very bad ally for Kassadin. By playing on the same side as Kassadin, she lowers their win rate by -3.4% to 46.6%. This demonstrates that there is an easy to overcome and exploit strategic relationship between Kassadin and Yuumi that allows them to perform not as well together than without each other.
Yuumi has a much lower diffuclty than Kassadin. That means you don't need to be cautious when enlisting Yuumi teammates to fight alongside, as they will have to have a much lower level of skill to fight well with you.
Fighting cooperatively, you will likely witness an overall large increase in your team’s capacity to deal magical damage. Together, these champions can blast through enemies with magic damage.
Although, by grouping Kassadin and Yuumi together, you will not be granting your team much protection for burst damage. Make sure to have other champs on your team that offsets this relative gap in their capabilities.
Regardless of your Yuumi ally's skill level, you should focus on maximizing your income, staying alive by avoiding foolish fights, and clearing objectives. If you do this, you will do well anyway.
If you would like to learn all of the intricacies of Kassadin in order to work well with Yuumi during both the early game and mid / late game phases of League rounds, you should continue reading to gather a few extra tricks and insights into this champion pairing. If you mind the build and tips presented above, you will grow your win rate significantly.
The most crucial finished items to focus on in your Kassadin and Yuumi synergy build consist of Seraph's Embrace, Stormsurge, and Rod of Ages. When Kassadin included at least these three finished items in his build, he did significantly better when fighting alongside Yuumi than with many other common item sets. In fact, Kassadin boasted an average winrate of 46.6% when synergizing his build and playstyle to Yuumi with these items in his kit.
To have the best likelihood of crushing your oponents, Kassadin players should use the First Strike, Magical Footwear, Future's Market, Cosmic Insight, Sudden Impact, and Ultimate Hunter runes from the Inspiration and Domination rune sets. Of all the rune sets players chose for this champion pairing, this mixture of runes yielded the top win rate. Moreover, these runes gave a 46.6% win rate overall.
If you need to view Kassadin and Yuumi cooperations tips and stats for a a particular rank, feel free to choose one from the selection menu above. By default, the statistics and guides displayed are computed using all matches run with these champs.