Karthusvs Kai'Sa
Karthus vs Kai'Sa is a decisive matchup in LoL patch 26.19. Karthus wins with a 75.0% win rate (+50.0%) over Kai'Sa based on 8 games. Karthus holds the advantage in both the early and late game. Below you'll find the best Karthus build, runes, laning stats, and strategies for the Karthus vs Kai'Sa matchup.
Karthus Matchup Breakdown
Use the dropdown to select an opponent and see a detailed breakdown of how Karthus performs against them. You'll get head-to-head win rates, laning stats, the best build and runes for the matchup, and early vs late game analysis — all based on real ranked data.
Who wins Karthus vs Kai'Sa?
Karthus wins 81.0% of these games. With this many games the true rate is most likely between 60.0% and 92.3% (95% range).
- Expected
- 59.4% From both champions' overall Bot win rates
- Matchup effect
- +21.6 pts Observed minus expected
- Sample
- 21 games Lane: Bot
- vs patch 26.18
- — Not enough games on both patches
Lane: Bot · Ranked Solo/Duo & Flex · North America server · All ranks · Patch 26.19 · Sep 24 – Sep 28
Key takeaways
- Karthus is favored in this matchup: Karthus wins 81.0% of 21 games, and the whole 95% range (60.0–92.3%) is on the same side of 50%.
- That is 21.6 points better for Karthus than both champions' overall Bot win rates predict (59.4%), so the matchup itself favors this pick — not just champion strength.
- Karthus players pick Shadowflame much less often against Kai'Sa: 84.0% of their other Bot games, 66.7% here.
How we calculate this
Games: ranked Solo/Duo and Flex games on the North America server from the patch shown. Remakes (games under 5 minutes) are excluded.
A game only counts when Karthus and Kai'Sa played the same position on opposite teams, so roaming, lane swaps within a team or a champion merely being in the same game never count as this matchup.
The 95% range is a Wilson score interval. Confidence comes from how wide that range is: within ±3 points is very high, ±5 high, ±8 moderate, anything wider low. Below 20 games a matchup is not classified at all.
Expected win rate combines both champions’ win rates in this lane (same games and filters) with the log5 formula: E = A(1−B) / (A(1−B) + B(1−A)). Matchup effect = observed − expected.
"What changes" compares Karthus's choices in this matchup with the same champion's other games in the same lane, and lists a change only when it is at least 3 points and statistically significant (two-proportion z-test, |z| ≥ 2, 20+ games).
Results are not split by rank: the sample per rank is too small for honest per-rank matchup numbers.
Karthus vs Kai'Sa Laning Stats
Only 20 games have a 15-minute snapshot so far — the lane-phase numbers appear from 30.
Whole-game averages
Karthus vs Kai'Sa Win Rate by Game Length
Karthus's win rate against Kai'Sa by game length. The dot is the win rate, the bar its 95% range and the dashed line the champion's usual win rate at that length. Lengths with fewer than 25 games are left blank.
No game length stands out: Karthus's results against Kai'Sa in short and long games are within the margin of error of each other.
Karthus vs Kai'Sa Power Spikes
Who is ahead at each stage, measured from these games. A stage reads "Even" when the difference is inside the margin of error, and "Insufficient data" when there are too few games to tell.
- Lane (15 min)Insufficient data
- First itemInsufficient data
- Games under 20 minInsufficient data
- 20–30 min gamesInsufficient data
- 30+ min gamesInsufficient data
What Karthus Changes Against Kai'Sa
Choices Karthus players make noticeably more or less often in this matchup than in their other Bot games.
ShadowflameItemUsually84.0%vs Kai'Sa66.7%−17.3 pts
DominationSecondary treeUsually2.4%vs Kai'Sa14.3%+11.9 pts
Amplifying Tome + Doran's Ring + Health Potion + Health PotionStarting itemsUsually2.7%vs Kai'Sa14.3%+11.6 pts
Manaflow BandRuneUsually3.7%vs Kai'Sa14.3%+10.5 pts
Sapphire Crystal + Doran's Ring + Health Potion + Health Potion + Health Potion + Stealth WardStarting itemsUsuallyunder 0.5%vs Kai'Sa4.8%+4.8 pts
Sapphire Crystal + Amplifying Tome + Doran's Ring + Dark Seal + Health Potion + Health PotionStarting itemsUsuallyunder 0.5%vs Kai'Sa4.8%+4.8 pts- W > Q > Ethe W > Q > E skill orderSkill priorityUsuallyunder 0.5%vs Kai'Sa4.8%+4.8 pts
Flash + HealSummoner spellsUsually0.3%vs Kai'Sa4.8%+4.4 pts
Best Karthus Build vs Kai'Sa
Usual Karthus build (Bot)
73.7% win rate · 19 games
Against Kai'Sa
Not enough matchup-specific build data: only 2 of 14 Karthus games against Kai'Sa carried a complete build, which is too few to recommend an item path from. Use Karthus's standard build instead.
- Karthus usually completes Blackfire Torch first, at 9.4 min (median of 20 games).
- Skill priority: Q > E > W — the same as usual.
Builds are ranked by the lower edge of their win rate range, not the raw win rate, so a build seen in a handful of wins never outranks a proven one.
Best Karthus Runes vs Kai'Sa
Usual Karthus runes (Bot)
Deathfire Touch
69.4% win rate · 36 games
Against Kai'Sa
Too few games for a matchup-specific rune page yet — use the usual page.
Plan your Karthus draft in Draft Lab
Draft Lab lays out both teams lane by lane with live matchup win rates, damage profiles and game-phase lean, and suggests picks and bans from current meta data.
- Full 5v5 draft board
- Lane matchup win rates
- Pick and ban suggestions
Karthus matchup data for League of Legends patch 26.19. The table below shows Karthus's win rate, gold difference, and performance stats against every champion in the current meta. Click any champion name to see a detailed head-to-head breakdown including the best Karthus build, runes, laning stats, and early vs late game analysis for that specific matchup.
Other Karthus Matchups
Hardest for Karthus
Easiest for Karthus
Win rate and games for each matchup. Lists are ranked by the edge of the 95% range so small samples cannot top them; matchups with at least 50 games only.
Help us maintain accuracy! If you notice incorrect stats, missing data, or any issues, your feedback directly improves the quality of our data for the entire community.
Karthus vs Kai'Sa FAQ - Patch 26.19
Who wins Karthus vs Kai'Sa?
Karthus is favored in this matchup: Karthus wins 81.0% of 21 games, and the whole 95% range (60.0–92.3%) is on the same side of 50%.
What is Karthus's win rate against Kai'Sa?
Karthus wins 81.0% of 21 Bot games against Kai'Sa on patch 26.19 (95% range 60.0–92.3%). Based on both champions' overall Bot win rates, 59.4% would be expected.
Does Karthus counter Kai'Sa?
Yes. Karthus wins 81.0% of 21 games against Kai'Sa on patch 26.19, and the whole 95% range is above 50%.
Who wins lane, Karthus or Kai'Sa?
There are not enough games with a 15-minute snapshot yet (20) to say who wins lane.
Does Karthus outscale Kai'Sa?
There are too few games of each length to tell yet.
When is Kai'Sa strongest against Karthus?
On current data there is no stage of the game where Kai'Sa is ahead of Karthus beyond the margin of error.
What should Karthus build against Kai'Sa?
There are not enough games for a matchup-specific core, so use Karthus's usual Bot core: Stormsurge, Shadowflame, Rabadon's Deathcap. The biggest change against Kai'Sa: Shadowflame (84.0% usually, 66.7% here).
What runes should Karthus use against Kai'Sa?
Use Karthus's usual Deathfire Touch page (Sorcery + Precision); there are too few games for a matchup-specific page. The biggest change against Kai'Sa: Domination (2.4% usually, 14.3% here).