Best Karthus Synergies

The best partner with Karthus is Zed Mid. The pair wins 50.7% across 2,905 games, 3.0 points more than the two champions' own win rates predict. Yasuo Mid (+2.8 over 3,260 games) and Yone Mid (+1.9 over 3,692 games) also over-perform. Based on Low Elo Ranked Solo/Duo games, patches 26.20-26.22. These are observed associations, not guaranteed outcomes. The weakest listed synergies for Karthus are Syndra Mid, Malzahar Mid, Veigar Mid, Lux Support, Galio Mid, Viktor Mid, Ahri Mid, Seraphine Support, Morgana Support, and Senna Support. The detailed info below lists each partner with observed win rate, expected win rate delta, sample size, rank scope, and patch window.

Updated 2026-11-15. Data is current for LoL patch 26.22 (all regions, low elo and high elo).

Top 10 Low Elo Karthus strongest synergies

  1. Zed Mid - 50.7% win rate with Karthus Jungle (+3.0 points vs expected), 2,905 games.
  2. Yasuo Mid - 50.8% win rate with Karthus Jungle (+2.8 points vs expected), 3,260 games.
  3. Yone Mid - 51.4% win rate with Karthus Jungle (+1.9 points vs expected), 3,692 games.
  4. Blitzcrank Support - 52.2% win rate with Karthus Jungle (+1.1 points vs expected), 1,778 games.
  5. Nautilus Support - 50.4% win rate with Karthus Jungle (+1.1 points vs expected), 2,987 games.
  6. Alistar Support - 51.4% win rate with Karthus Jungle (+1.0 points vs expected), 1,130 games.
  7. Thresh Support - 49.3% win rate with Karthus Jungle (+0.7 points vs expected), 3,089 games.
  8. Katarina Mid - 49.4% win rate with Karthus Jungle (+0.7 points vs expected), 1,222 games.
  9. Leona Support - 51.4% win rate with Karthus Jungle (+0.6 points vs expected), 2,572 games.
  10. Pyke Support - 46.5% win rate with Karthus Jungle (+0.5 points vs expected), 1,424 games.

Top 10 Low Elo Karthus weakest synergies

  1. Syndra Mid - 44.2% win rate with Karthus Jungle (-1.9 points vs expected), 1,283 games.
  2. Malzahar Mid - 48.3% win rate with Karthus Jungle (-1.4 points vs expected), 1,474 games.
  3. Veigar Mid - 45.6% win rate with Karthus Jungle (-1.4 points vs expected), 1,178 games.
  4. Lux Support - 47.7% win rate with Karthus Jungle (-1.1 points vs expected), 2,539 games.
  5. Galio Mid - 45.2% win rate with Karthus Jungle (-1.1 points vs expected), 1,037 games.
  6. Viktor Mid - 45.4% win rate with Karthus Jungle (-1.0 points vs expected), 1,199 games.
  7. Ahri Mid - 48.4% win rate with Karthus Jungle (-0.9 points vs expected), 2,041 games.
  8. Seraphine Support - 48.7% win rate with Karthus Jungle (-0.9 points vs expected), 2,243 games.
  9. Morgana Support - 49.1% win rate with Karthus Jungle (-0.8 points vs expected), 1,661 games.
  10. Senna Support - 45.2% win rate with Karthus Jungle (-0.7 points vs expected), 1,316 games.

Top 10 High Elo Karthus strongest synergies

  1. Zed Mid - 53.0% win rate with Karthus Jungle (+2.2 points vs expected), 2,822 games.
  2. Qiyana Mid - 53.9% win rate with Karthus Jungle (+1.7 points vs expected), 1,043 games.
  3. Yasuo Mid - 55.2% win rate with Karthus ADC (+1.2 points vs expected), 1,169 games.
  4. Nautilus Support - 52.3% win rate with Karthus Jungle (+1.1 points vs expected), 2,419 games.
  5. Yasuo Mid - 50.3% win rate with Karthus Jungle (+1.0 points vs expected), 2,157 games.
  6. Yone Mid - 49.6% win rate with Karthus Jungle (+0.9 points vs expected), 2,703 games.
  7. Nautilus Support - 55.4% win rate with Karthus ADC (+0.9 points vs expected), 1,631 games.
  8. Zed Mid - 57.9% win rate with Karthus ADC (+0.8 points vs expected), 1,253 games.
  9. Katarina Mid - 53.5% win rate with Karthus Jungle (+0.8 points vs expected), 1,101 games.
  10. Alistar Support - 53.9% win rate with Karthus Jungle (+0.7 points vs expected), 1,557 games.

Top 10 High Elo Karthus weakest synergies

  1. Syndra Mid - 46.4% win rate with Karthus Jungle (-1.6 points vs expected), 1,111 games.
  2. Senna Support - 49.8% win rate with Karthus Jungle (-0.9 points vs expected), 1,007 games.
  3. Nami Support - 48.3% win rate with Karthus Jungle (-0.7 points vs expected), 1,794 games.
  4. Viktor Mid - 47.9% win rate with Karthus Jungle (-0.6 points vs expected), 1,014 games.
  5. Lulu Support - 51.2% win rate with Karthus Jungle (-0.6 points vs expected), 2,607 games.
  6. Janna Support - 48.2% win rate with Karthus Jungle (-0.5 points vs expected), 1,144 games.
  7. Ahri Mid - 50.4% win rate with Karthus Jungle (-0.5 points vs expected), 1,269 games.
  8. Yuumi Support - 49.9% win rate with Karthus Jungle (-0.4 points vs expected), 1,044 games.
  9. Milio Support - 49.1% win rate with Karthus Jungle (-0.4 points vs expected), 1,258 games.
  10. Braum Support - 53.8% win rate with Karthus Jungle (-0.2 points vs expected), 1,039 games.

How these matchup statistics are calculated

Counter and synergy statistics use Ranked Solo/Duo games, exclude matches shorter than 600 seconds, and group results by patch window, region, rank scope, and champion role.

Pairwise pages use a rolling three-patch window and compare observed win rate with a log-odds expected win rate based on each champion's role-adjusted baseline; listed pairs require at least 1,000 games.

Read the full methodology for the model and guidance on interpreting these results.