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 stats shown here emphasize some critical Kassadin against Yuumi matchup stats that may help us distinguish the differences between this pair of champs. Kassadin’s KDA ratio ([kills + assists] / deaths) of NaN is more than Yuumi’s KDA ratio of NaN, indicating that Kassadin may be more central to his team's team fighting capability than Yuumi. This observation is largely caused by the difference in kills.
Kassadin often has a much larger longest kill spree than his counter does. On average, he takes more damage than Yuumi. This often reflects differing health capacities, yet it can also hint that the champion with more health has less agility and thus is not able to flee from additional harm when engaged or poked.
Both LoL champs are great. Both have their pros and cons. In the game's current meta, Kassadin usually wins when playing against Yuumi, with a 54.6% win rate. As a result, Kassadin makes a great counter to Yuumi.
While Kassadin does have a much higher winrate than Yuumi, when on opposite teams, Kassadin also has a much greater difficulty level that makes him a more challenging champ to learn and master. You don't need to be too worried when picking Kassadin into Yuumias his relative depth means that you may not be able to unleash his full potential without a significant amount of practice beforehand.
Furthermore, Kassadin has some amount of utility and CC, a similar amount to Yuumi. This makes her just as valuable during team fights, especially when facing champions with a lot of burst damage.
While there is not one best champion for every situation in League of Legends, in Kassadin vs Yuumi matchups, Kassadin is the better champion with a noticably higher win rate, more champion depth, and a similar amount of utility to help out your teammates during teamfights.
Kassadin is a great counter for Yuumi. Make sure you focus your tactics on maximizing your CS and taking out objectives. If you do that, you should be able to stand on your own as Kassadin against Yuumi.
If you would like to learn all of the intricacies of Kassadin in order to counter Yuumi during both the early game and mid / late game phases of League of Legends, you should keep reading to pick up a few extra tricks and insights into this matchup. If you listen to the build and tips shown above, you will grow your win rate significantly and be closer to League of Legends pro players.
Kassadin most often accumulates much more CS as Yuumi. Champs who on average don't take much CS typically don't need much CS to be valuable teammates, such as supports. These kinds of champions are able to scale properly off of their abilities and first items alone. Yet, champs with large amounts of CS, such as hyper-carries, typically require several high cost items to be effective. In either case, try to exceed the numbers displayed on this page to do well.
The top items to prioritize in your Kassadin versus Yuumi build consist of Seraph's Embrace, Malignance, and Rod of Ages. When Kassadin combined at least these three items in his build, he performed much better when facing Yuumi than with most other typical item sets. In fact, Kassadin had an average win rate of 54.6% when playing against Yuumi with these items in his kit.
To have the best likelihood of beating Yuumi as Kassadin, Kassadin players should take the First Strike, Magical Footwear, Future's Market, Cosmic Insight, Sudden Impact, and Ultimate Hunter runes from the Inspiration and Domination rune sets. Out of all the rune builds players used for Kassadin vs Yuumi fights, this mixture of runes yielded the greatest win rate. Notably, these runes provided a 54.6% win rate overall.
By default, tips, stats, and builds on how to beat Yuumi as Kassadin are shown for all ranked divisions combined. If you would like to scope the statistics and builds to a specific rank, you may use the selection menu located earlier in the counter matchup guide.