Make sure you choose the right augment at the right time.
Death Ray is a powerful poke and a strong area of denial tool. Use it in combination with Gravity Field to control your enemy's position.
When Rek'Sai is near, she can see the position of you and your allies, but only if you're moving.
If you see one of Rek'Sai's tunnels, briefly stand on one of the entrances to destroy it.
Rek'Sai's Furious Bite gains damage as she builds Fury. Be very careful around her when her Fury is full.
The stats shown here underscore several vital Viktor against Rek'Sai matchup statistics that can help us interpret the differences and similarities between the two. As an example, Viktor’s KDA ratio ([kills + assists] / deaths) of NaN is greater than Rek'Sai’s KDA ratio of NaN, indicating that Viktor may be more central to his team's team fighting capability than Rek'Sai..
Viktor usually has a similar longest killing spree as his opponent does. Typically, he takes less damage than Rek'Sai. This typically indicates differing health capacities, yet it can also hint that the champion with more HP has less mobility and thus is not able to escape further damage when poked or engaged.
Both LoL champs are great champions. Both champs have their pros and cons. In League's current meta, Viktor usually fairs equally well when playing against Rek'Sai, with a 49.4% win rate. Therefore, Viktor makes an ok counter to Rek'Sai.
While Viktor does have a lower win rate than Rek'Sai, when facing one another, Viktor also has a much greater level of difficulty that makes him a more time consuming character to pick up and master. You should be careful when picking Viktor into Rek'Saias his relative depth means you may not be able to reach his full potential without a significant amount of practice beforehand.
Moreover, Viktor has almost no amount of utility and CC, a similar amount to Rek'Sai. This makes her just as valuable during team fights, especially when fighting champions with a ton of burst damage.
While there is not one best champion for every situation in League of Legends, in Viktor vs Rek'Sai matchups, Rek'Sai is the better champ with a similar win rate, more champion depth, and a similar amount of utility to help out your team members during late stage team fights.
Viktor is a somewhat poor counter to Rek'Sai. Make sure you focus your play on maximizing your gold and cs and destroying objectives. If you can do that, you should be able to stand on your own as Viktor against Rek'Sai.
If you would like to truly master Viktor to counter Rek'Sai during both the early game and mid / late game phases of League of Legends, you should continue reading to pick up a few extra lessons on this matchup. If you pay attention to the build and tips displayed here, you will increase your win rate by a lot and be closer to League of Legends pro players.
Viktor often gets much more CS relative to Rek'Sai. Champs who on average don't take many minion kills often 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, champs with a lot of CS, such as hyper-carries, often have to have several high cost items to be effective. In either case, try to exceed the values reported on this page to do well.
The ideal items to prioritize in your Viktor versus Rek'Sai build include Shadowflame, Stormsurge, and Luden's Companion. When Viktor bought at least these three pieces in his build, he did a lot better vs. Rek'Sai than with many other commonly used counter builds. In fact, Viktor boasted an average win rate of 49.4% when countering Rek'Sai with these items in his kit.
To have the highest likelihood of crushing Rek'Sai as Viktor, Viktor players should use the First Strike, Magical Footwear, Biscuit Delivery, Cosmic Insight, Manaflow Band, and Transcendence runes from the Inspiration and Sorcery rune sets. Of all the rune combinations players picked for Viktor vs Rek'Sai battles, this order of runes yielded the highest win rate. Notably, these runes gave a 49.4% win rate overall.
If you want to see Viktor versus Rek'Sai tips and counter builds for a a particular skill level, please choose one from the selection menu shown above. If viewing for the first time, the statistics and build suggestions given are computed using all matches played with these champions.