Keeping tunnels spread out across the map will ensure you have choices when you want to cast Void Rush.
Cast Burrow before travelling around the map to take advantage of the increased Move Speed and the safety provided by Tremor Sense.
Tremor Sense can warn you of enemies closing in, and is particularly useful when entering enemy territory.
Karthus can cast spells for a short duration after he is killed. Move away from his corpse to be safe.
Make sure you always have enough health to survive Requiem, even if you have to go back to the base more frequently to heal.
The stats shown on this page emphasize several vital Rek'Sai vs. Karthus counter stats that can help us explain the differences and similarities between this set of champions. As an example, Rek'Sai’s KDA ratio ([kills + assists] / deaths) of NaN is more than Karthus’s KDA ratio of NaN, demonstrating that Rek'Sai may be more central to his team's team fighting potential than Karthus..
Rek'Sai often has a similar longest kill spree as his matchup does. On average, he receives more damage than Karthus. This often reflects different amounts of tankyness; however, it can also imply that the one champ has less agility and thus is not able to kite away from further damage when engaged or poked.
Both League of Legends champions are great. Both have their strengths, weaknesses, and counters. In the game's current meta, Rek'Sai usually wins when trying to fight Karthus, with a 52.3% win rate. As a result, Rek'Sai makes a good counter to Karthus.
While Rek'Sai does have a higher win rate compared to Karthus, when facing one another, Rek'Sai also has a much lower difficulty level that makes him a less challenging character to develop with. You should be be fine when picking Rek'Sai into Karthus.
Additionally, Rek'Sai has some amount of utility and CC, a similar amount to Karthus. This makes her just as valuable during team fights, especially when facing champions with a ton of burst damage.
While there isn't one best champion in League of Legends, in Rek'Sai vs Karthus matchups, Rek'Sai is the better champion with a noticably higher win rate, less champion complexity, and a similar amount of utility to help out your allies during late stage team fights.
Rek'Sai is an above average counter for Karthus. You will do well by focussing your strategy on keeping up your gold and cs and clearing objectives. If you do that, you should hold your own as Rek'Sai against Karthus.
To truly master Rek'Sai to counter Karthus during both the early game and mid / late game phases of League of Legends, you should keep reading to gather a few extra tricks and insights into this matchup. If you mind the build and stats shown here, you will increase your win rate by a lot and be that much closer to League of Legends pro players.
Rek'Sai most often accumulates less CS relative to Karthus. Champs who on average don't get much CS often don't need much CS to be valuable teammates, such as supports. They are capable of scaling properly off of their abilities and first items alone. Yet, champions with a lot of CS, such as hyper-carries, usually need a lot of items to be effective. In either case, try to do better than the numbers reported on this page to do well.
The top items to use in your Rek'Sai versus Karthus build include Sterak's Gage, Black Cleaver, and Titanic Hydra. When Rek'Sai bought at least these three items in his build, he performed significantly better vs Karthus than with many other typical counter builds. In fact, Rek'Sai had an average win rate of 52.3% battling Karthus with these items in his kit.
To have the best likelihood of vanquishing Karthus as Rek'Sai, Rek'Sai players should take the Conqueror, Triumph, Legend: Alacrity, Coup de Grace, Magical Footwear, and Cosmic Insight runes from the Precision and Inspiration rune sets. Of all the rune combinations players used for Rek'Sai vs Karthus matchups, this combo of runes yielded the greatest win rate. Notably, these runes gave a 52.3% win rate overall.
If you need to see Rek'Sai vs Karthus tips and counter stats for a a particular player tier, please select one from the selection menu provided above. If viewing for the first time, the stats and guides given are computed using all rounds run with both champs.