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.
Vi cannot be stopped while using her ult. Remember to save your displacement effects until after she's done charging.
A fully charged Vault breaker deals double damage. If you see Vi start to charge you should back off or try to dodge it.
Vi will shred your Armor and gain Attack Speed if she manages to hit you three times in a row. Try not to engage in extended brawls with her.
The stat comparisons provided here highlight some strategic Kassadin versus Vi matchup statistics that may help us grasp the differences and similarities between the pair. As an example, Kassadin’s KDA ratio ([kills + assists] / deaths) of NaN is more than Vi’s KDA ratio of NaN, demonstrating that Kassadin may be more central to his team's team fighting capability than Vi..
Kassadin normally has a similar longest killing spree as his foe does. Commonly, he receives a similar amount of damage to Vi. This is usually reflective of different amounts of tankyness, but it can also indicate that the champ with higher HP has less agility and thus is not able to kite away from additional damage when poked or engaged.
Both League of Legends champions are great champions. Both have their strengths, weaknesses, and counters. In the game's current meta, Kassadin usually loses when trying to fight Vi, with a 47.2% win rate. Thus, Kassadin makes a bad counter for Vi.
While Kassadin does have a lower win rate than Vi, when facing one another, Kassadin also has a much greater level of difficulty that makes him a more complex character to develop with. You should expect to face a difficult match when picking Kassadin into Vias his relative depth means that you may not be able to reach his full potential without a lot of practice beforehand.
Moreover, Kassadin also has some amount of CC and other utility, a similar amount to Vi. This makes her just as valuable during team fights, especially when fighting champions with a lot of burst damage.
While there is not a single best champion overall in League of Legends, in Kassadin vs Vi matchups, Vi is the better champion with a lower win rate, more champion depth, and a similar amount of utility to help out your allied champions during teamfights.
Kassadin is a bad counter for Vi. Focus your gameplay on increasing your CS and clearing objectives. If you are able to do that, you should hold your own as Kassadin against Vi.
To truly master Kassadin to counter Vi 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 mind the build and stats shown above, you will grow your win rate significantly and be that much closer to League of Legends pro players.
Kassadin usually racks up much more CS relative to Vi. Champs who on average don't acquire much CS usualy don't require much CS to be valuable teammates, such as supports. They are capable of scaling well off of their skills, stats, and first items alone. Yet, champions with a lot of CS, such as hyper-carries, usually have to have many items to be effective. In either case, try to surpass the values shown on this page to do well.
The best items to have in your Kassadin versus Vi build include Seraph's Embrace, Rabadon's Deathcap, and Zhonya's Hourglass. When Kassadin used at least these three items in his build, he performed significantly better when fighting Vi than with many other typical item sets. In fact, Kassadin boasted an average win rate of 47.2% when countering Vi with this counter build.
To have the best probability of crushing Vi 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 sets players chose for Kassadin vs Vi matchups, this combo of runes yielded the greatest win rate. Notably, these runes averaged a 47.2% winrate overall.
By default, tips, statistics, and builds on how to beat Vi as Kassadin are given for all skill levels combined. To scope the stats and builds to a specific player tier, you can use the selection menu earlier in the counter matchup guide.