The champions that counter Karthus hardest in bot lane are Kog'Maw (43.71%), Senna (44.27%) and Veigar (45.21%) — those are Karthus's own pooled win rates. The easiest matchups are Heimerdinger (56.12%), Corki (55.72%) and Swain (55.19%).
29 researched matchup guides for Karthus in bot lane, most-played first. Win rates are Karthus's side, pooled Emerald+ games sampled July 2026.
| Matchup | Win rate | Games | Favour |
|---|---|---|---|
| Karthus vs Caitlyn | 51.73% | 3,998 | Leans Karthus |
| Karthus vs Jhin | 50.19% | 3,720 | Even |
| Karthus vs Ezreal | 49.99% | 3,599 | Even |
| Karthus vs Kai'Sa | 53.56% | 3,204 | Leans Karthus |
| Karthus vs Jinx | 47.95% | 2,780 | Leans Jinx |
| Karthus vs Ashe | 51.03% | 2,430 | Leans Karthus |
| Karthus vs Senna | 44.27% | 2,234 | Senna favoured |
| Karthus vs Lucian | 50.5% | 1,998 | Even |
| Karthus vs Tristana | 49.71% | 1,861 | Even |
| Karthus vs Sivir | 47.08% | 1,612 | Leans Sivir |
| Karthus vs Miss Fortune | 48.05% | 1,588 | Leans Miss Fortune |
| Karthus vs Seraphine | 50.16% | 1,545 | Even |
| Karthus vs Aphelios | 51.06% | 1,471 | Leans Karthus |
| Karthus vs Twitch | 50.18% | 1,393 | Even |
| Karthus vs Smolder | 48.21% | 1,230 | Leans Smolder |
| Karthus vs Vayne | 48.93% | 1,216 | Leans Vayne |
| Karthus vs Draven | 50.76% | 1,180 | Leans Karthus |
| Karthus vs Ziggs | 47.58% | 1,158 | Leans Ziggs |
| Karthus vs Samira | 52.53% | 1,146 | Leans Karthus |
| Karthus vs Zeri | 48.98% | 1,025 | Leans Zeri |
| Karthus vs Xayah | 45.89% | 852 | Leans Xayah |
| Karthus vs Varus | 51.55% | 712 | Leans Karthus |
| Karthus vs Kalista | 50.43% | 577 | Even |
| Karthus vs Swain | 55.19% | 433 | Karthus favoured |
| Karthus vs Kog'Maw | 43.71% | 421 | Kog'Maw favoured |
| Karthus vs Veigar | 45.21% | 407 | Leans Veigar |
| Karthus vs Nilah | 48.92% | 325 | Leans Nilah |
| Karthus vs Corki | 55.72% | 323 | Karthus favoured |
| Karthus vs Heimerdinger | 56.12% | 139 | Karthus favoured |