MacroMind matchup data — real ranked games, not opinions
Jax vs Karthus
How often does Jax beat Karthus in Jungle?
Jax into Karthus in Jungle: 48% observed win rate across 190 ranked games. Counted from real matches, and every number here shows its sample size.
By 15 minutes the median game has Jax behind by 529 gold.
Does Jax counter Karthus?
Too close for a counter call: Jax sits at 48% over 190 games, inside the noise band. On this sample neither pick counters the other — the swing lives in the conditions below, so play the side you know better.
Beating Karthus: the Jax game plan
A 300-gold lead at 10:00 puts Jax at 61% across 62 games. Flip the lead and Jax falls to 42% across 128.
| The spot | Win rate | Games |
|---|---|---|
| 300 gold up at 10:00 | 61% | 62 |
| 300 gold down at 10:00 | 42% | 128 |
| First blood | 53% | 129 |
| +kills at 10:00 | 62% | 82 |
| 0 deaths at 10:00 | 53% | 43 |
Someone usually dies here around 6:16 in the median game, and level 6 lands near 7:20. Until your spike is online, respect the all-in.
Jax's Jungle build, with receipts
Into Karthus specifically, Jax finishes Trinity Force first most often: 55.3% over 47 games of this matchup.
The most-finished Jax core is Trinity Force, Sundered Sky, Zhonya's Hourglass: 58.9% across 2,303 games when all three got done. All matchups, patches 16.1-16.12.
Most games start Gustwalker Hatchling + Health Potion; the first finished item is usually Trinity Force (9,957 games).
Skill plan: Jax players max W first and take E at level 1.