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.
The Karthus Vex synergy stats shown here demonstrate the areas of his gameplay that do better (or worse) when paired with Vex, 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 Vex. His KDA fell from NaN to NaN. This negative change shows that Vex helps Karthus perform worse in ranked LoL rounds. Yet, the small difference shows that this performance change is not very impactful.
When Karthus tries to synergize with Vex, he gets a little decrease in his full damage dealt. This could demonstrate that Vex does not provide cover for him to dish out more damage or that their allyship also helps increase the match's duration. Similarly, when Karthus is played alongside Vex on the same team, he usually scores many fewer killing sprees compared to when he plays alone. This is contrasting evidence that he is worse when playing synergisticly with Vex.
Additionally, when Karthus plays with Vex on the same team, he often takes a little more damage than when he fights alone. Taking more damage could mean that Vex does a poor job of covering Karthus during teamfights.
There is no top champion pairing for Karthus that will always be his top synergy. Yet, Vex is a below average ally for Karthus. By locking into the same team as Karthus, they decreases their win rate by -1.9% to 45.4%. This demonstrates that there is a harmful bond between Karthus and Vex that results in them performing worse together than alone.
Vex has a much lower diffuclty than Karthus. That means you don't need to be cautious when arranging Vex teammates to play with, as they will have to have a much lower level of skill to play well with you.
Fighting cooperatively, Karthus players should expect to witness an overall large increase in your team’s ability to deal magic damage. Together, these two can blast through enemies with magic damage.
Conversely, by aligning Karthus and Vex together, you will not be giving your side a lot of attack damage. Make sure to include other champs on your team that nullifies this hole in this pairing's abilities.
Regardless of the ability of your Vex ally, you need to focus on maximizing your gold income, staying alive by avoiding foolish fights, and taking down objectives. If you heed this simple advice, you should do well, regardless.
If you would like to learn all of the intricacies of Karthus to synergize with Vex during both the early game and mid / late game phases of League of Legends rounds, you should keep reading to pick up a few extra tips and tricks for this champion pairing. If you pay attention to the build and tips presented here, you will increase your win rate significantly.
The most important finished items to get in your Karthus and Vex synergy build consist of Rabadon's Deathcap, Malignance, and Shadowflame. When Karthus incorporated at least these three great items in his build, he did a lot better as an ally of Vex than with most other typical builds. In fact, Karthus boasted an average winrate of 45.4% when synergizing his build and playstyle to Vex with these items in his kit.
To have the greatest probability of vanquishing your oponents, Karthus players should take the First Strike, Magical Footwear, Future's Market, Cosmic Insight, Eyeball Collection, and Ultimate Hunter runes from the Inspiration and Domination rune sets. Of all the runes that we analyzed for this team composition, this mix of runes yielded the greatest win rate. In fact, these runes averaged a 45.4% winrate overall.
By default, tips, stats, and builds on how to synergize Vex with Karthus are shown for all ranked divisions. If you want to narrow the stats and builds to a distinct player tier, you should use the selection menu located earlier in the counter matchup guide.