Lead your enemy when targeting with Noxious Blast to ensure the hit.
Use Twin Fang on poisoned stationary targets like monsters and units stunned by her Petrifying Gaze for maximum damage.
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 stat comparisons shown here clarify some strategic Cassiopeia versus Karthus counter stats that can help us grasp the differences and similarities between this set of champions. For instance, Cassiopeia’s KDA ratio ([kills + assists] / deaths) of NaN is more than Karthus’s KDA ratio of NaN, indicating that Cassiopeia may be more central to her team's team fighting capacity than Karthus..
Cassiopeia often has a similar longest kill spree as her matchup does. Commonly, she takes a similar amount of damage to Karthus. This often reflects differing health capacities, but it can also show that the champ with more HP has less mobility and thus is unable to flee from further damage when poked or engaged.
Both LoL champions are great champions. Both champs have their pros and cons. In League's current meta, Cassiopeia usually wins when playing against Karthus, with a 52.7% win rate. As a result, Cassiopeia makes a good counter to Karthus.
While Cassiopeia does have a higher win rate compared to Karthus, when on opposite teams, Cassiopeia also has a much greater difficulty level that makes her a more difficult character to develop with. You should be be fine when picking Cassiopeia into Karthusas her relative depth means you may not be able to reach her full potential without a significant amount of practice beforehand.
Furthermore, Cassiopeia has a good amount of utility and CC, a similar amount to Karthus. This makes her just as valuable during team fights, especially when trying to counter champions with a ton of burst damage.
While there is not one best champion overall in League of Legends, in Cassiopeia vs Karthus matchups, Cassiopeia is the better champ with a noticably higher win rate, more champion depth, and a similar amount of utility to help out your allied champions during teamfights.
Cassiopeia is an above average counter to Karthus. Make sure you focus your gameplay on increasing your gold and cs and destroying objectives. If you do that, you should hold your own as Cassiopeia against Karthus.
If you would like to learn all of the intricacies of Cassiopeia to counter Karthus during both the early game and mid / late game phases of League of Legends, you should continue reading to pick up a few extra tricks and insights into this matchup. If you pay attention to the build and tips shown here, you will increase your win rate significantly and be closer to League of Legends pro players.
Cassiopeia often racks up more CS as Karthus. Champs who typically don't get many minion kills often don't need much CS to be valuable teammates, such as sup champs. These kinds of champions are able to scale properly off of their abilities and first items alone. Yet, champs with large amounts of CS, such as hyper-carries, often have to have several high cost items to be effective. In either situation, try to surpass the values displayed on this page to do well.
The most important items to use in your Cassiopeia versus Karthus build include Liandry's Anguish, Seraph's Embrace, and Rylai's Crystal Scepter. When Cassiopeia included at least these three items in her build, she performed significantly better countering Karthus than with most other typical builds. In fact, Cassiopeia had an average win rate of 52.7% when countering Karthus with these items in her kit.
To have the best likelihood of defeating Karthus as Cassiopeia, Cassiopeia players should equip the Conqueror, Presence of Mind, Legend: Tenacity, Last Stand, Conditioning, and Overgrowth runes from the Precision and Resolve rune sets. Of all the rune builds players used for Cassiopeia vs Karthus counter picks, this blending of runes resulted in the highest win rate. Moreover, these runes gave a 52.7% winrate overall.
By default, tips, stats, and builds on how to beat Karthus as Cassiopeia are presented for all ranked divisions combined. If you would like to narrow the statistics and builds to an individual division, you should use the selection menu earlier on the page.