Lay Waste is very strong at farming minions and harassing enemy champions.
Ask your allies to help point out when you should use Requiem to get kills in different lanes.
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.
The Karthus Rek'Sai synergy stats shown here demonstrate the areas of his gameplay that do better (or worse) when paired with Rek'Sai, compared to his overall stats. Significant differences are areas of focus that highlight how his gameplay changes when paired with this other champion.
Overall, Karthus sees a very large drop in his KDA (ratio of kills and assists to deaths) when paired with Rek'Sai. His KDA fell from NaN to NaN. This decrease shows that Rek'Sai helps Karthus perform worse in competitive League rounds. Yet, the small difference proves that this performance change is only marginal.
When Karthus plays on the same team as Rek'Sai, he observes a little drop in his full damage output. This difference may signal that Rek'Sai doesn't help cover for him to deal more damage or that his presence on the team also helps extend the round's duration. Similarly, when Karthus is played with Rek'Sai on the same side, he usually scores many fewer killing sprees than when he plays alone. This is contrasting evidence that he is worse when playing alongside Rek'Sai.
Additionally, when Karthus plays with Rek'Sai on the same team, he typically takes much less damage than when he fights alone. Taking not as much damage could indicate that Rek'Sai does a decent job of covering Karthus during teamfights.
There is no top ally for Karthus that will always be his best ally. However, Rek'Sai is a top-tier ally for Karthus. By being on the same team as Karthus, he improves their win rate by 3.6% to 50.9%. This shows that there is an important bond between Karthus and Rek'Sai that results in them performing better together than without each other.
Rek'Sai has a much lower diffuclty than Karthus. That means you don't need to be careful when enlisting Rek'Sai comrades to fight alongside, as they will need a much lower level of skill to be able to cooperate well with you.
When playing alongside, you should expect to witness an overall large increase in your team’s capability to deal magic damage. Combined, these two can blast through enemies with magic damage.
Conversely, by pairing Karthus and Rek'Sai together, you probably will not be giving your team very much tankyness. Plan to pick other champs on your team that helps cover this hole in this pairing's abilities.
Regardless of your Rek'Sai ally's ability, you need to focus on maximizing your gold income, staying alive by avoiding foolish fights, and clearing objectives. If you do this, you should do well anyway.
To truly master Karthus in order to work well with Rek'Sai during both the early game and mid / late game phases of LoL rounds, you should continue reading to pick up a few extra lessons on this champion pairing. If you pay attention to the build and stats shown here, you will increase your win rate significantly.
The best finished items to prioritize in your Karthus and Rek'Sai synergy build include Rabadon's Deathcap, Cryptbloom, and Shadowflame. When Karthus included at least these three pieces in his build, he performed much better when paired up with Rek'Sai than with many other typical item sets. In fact, Karthus boasted an average win rate of 50.9% when synergizing his build and playstyle to Rek'Sai with these items in his kit.
To have the best probability of defeating your oponents, Karthus players should take the Dark Harvest, Cheap Shot, Eyeball Collection, Treasure Hunter, Presence of Mind, and Last Stand runes from the Domination and Precision rune sets. Of all the runes that we analyzed for this team composition, this blending of runes yielded the greatest win rate. In fact, these runes averaged a 50.9% winrate overall.
By default, tips, statistics, and builds on how to pair Rek'Sai with Karthus are displayed for all skill levels combined. To filter the statistics and builds to a particular division, you should use the selection menu earlier in the counter matchup guide.