You can use Comet of Legend's flight to grow Starsurge to massive proportions.
Comet of Legend allows you to move quickly around the map; use it to put pressure on other lanes.
Save Voice of Light to use as a defense against melee opponents if you need to - otherwise, use its slow to start a fight at long range.
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 Aurelion Sol Karthus synergy stats shown here demonstrate the areas of his gameplay that do better (or worse) when paired with Karthus, compared to his overall stats. Significant differences are areas of focus that highlight how his gameplay changes when paired with this other champion.
Overall, Aurelion Sol sees a large worsening in his KDA (ratio of kills and assists to deaths) when paired with Karthus. His KDA fell from NaN to NaN. This decrease shows that Karthus helps Aurelion Sol perform not as well in competitive League games. Yet, the small difference demonstrates that this performance change is not very impactful.
When Aurelion Sol is an ally to Karthus, he sees a little decrease in his complete damage output. This may demonstrate that Karthus does not help cover for him to deal more damage or that his allyship also helps increase the game's duration. Similarly, when Aurelion Sol is played with Karthus on the same team, he usually scores many fewer killing sprees than when he plays alone. This is contrasting evidence that he is worse when playing synergisticly with Karthus.
Moreover, when Aurelion Sol plays with Karthus on the same side, he on average takes a little more damage than when he fights alone. Receiving more damage could indicate that Karthus does a poor job of covering Aurelion Sol during teamfights.
There is no one best ally for Aurelion Sol that will no matter what be his #1 synergy. However, overall, Karthus is a very typical companion for Aurelion Sol. By playing on the same team as Aurelion Sol, he drops their win rate by -0.3% to 50.3%. This signals that there is only a small strategic relationship between Aurelion Sol and Karthus that results in them performing not as well together than without each other.
Karthus has a lower difficulty than Aurelion Sol. That means Aurelion Sol players don't need to be cautious when finding Karthus comrades to play with, as they will have to have a lower level of skill to play well with you.
Working alongside, Aurelion Sol players should expect to observe an overall large increase in your team’s capability to to do a lot of AP damage. Together, these champs are able to dish out a surprising amount of magic type damage.
Conversely, by pairing Aurelion Sol and Karthus together, you probably will not be giving your other allies a great deal of sustained damage output. We recommend you pick other champs on your team that offsets this relative hole in their kit.
Regardless of your Karthus ally's ability, you should focus on increasing your gold income, outlasting your enemies, and clearing objectives. If you do this, you should do well anyway.
If you would like to truly master Aurelion Sol in order to synergize with Karthus during both the laning and mid / late game phases of LoL matches, you should keep reading to learn additional tricks and insights into this champion pairing. If you pay attention to the build and stats shown above, you should grow your win rate significantly.
The most important finished items to get in your Aurelion Sol and Karthus synergy build include Rabadon's Deathcap, Rylai's Crystal Scepter, and Liandry's Torment. When Aurelion Sol incorporated at least these three finished items in his build, he did significantly better when fighting alongside Karthus than with many other common builds. In fact, Aurelion Sol boasted an average winrate of 50.3% when synergizing his build and playstyle to Karthus with this build.
To have the greatest probability of crushing your oponents, Aurelion Sol players should equip the Arcane Comet, Manaflow Band, Transcendence, Gathering Storm, Magical Footwear, and Minion Dematerializer runes from the Sorcery and Inspiration rune sets. Of all the runes players picked for Aurelion Sol and Karthus pairings, this sequence of runes resulted in the top win rate. In fact, these runes provided a 50.3% win rate overall.
By default, tips, stats, and builds on how to pair Karthus with Aurelion Sol are given for all skill levels, merged. If you would like to narrow the stats and builds to a particular player tier, you should use the selection menu located earlier in the counter matchup guide.