League Classic matchup
Ahri vs Karthus
The lane, from both sides
Ahri’s side
- Strong against Karthusfrom the AP Assassin build (Mid)
Karthus's lack of mobility makes him vulnerable to Ahri's
CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds.-into-burst combo.
Karthus’s side
- Weak against Ahrifrom the AP Burst Mage build (Jungle)CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds. interrupts the
RequiemRequiemRActive: Karthus channels for 3 seconds, then deals magic damage to all targetable enemy champions upon completion. channel, and 
Spirit RushSpirit RushRActive: Ahri dashes to the target location and then fires 3 essence bolts at nearby enemies, prioritizing champions, dealing magic damage. Spirit Rush can be recast up to 2 more times within 10 seconds. Recast: Ahri mimics the first cast's effects. covers three times the ground 
Wall of PainWall of PainWActive: Karthus erects a wall of pain at the target location perpendicular to his facing that lasts 5 seconds, granting sight around its pillars and center. Enemies that touch the wall are inflicted with magic penetration and become slowed for 5 seconds, decaying over the duration. This can affect enemies only once per cast. can slow. Karthus's only defence is a wall Ahri dashes past.
The lane in detail
AhriKarthusAhri picks the moment, Karthus picks the ground
Lay Waste is placed on the ground. Charm stops at the first body it touches.
Killing Karthus does not end the exchange. 
Death DefiedDeath DefiedPassiveInnate: Upon taking fatal damage, Karthus enters a zombie state for 7 seconds, during which he can cast his abilities at no cost. If Defile has been learned, it will remain toggled on for Death Defied's entire duration. Requiem becomes disabled after 4 seconds of the duration have elapsed. While under this state, Karthus becomes untargetable and immune to crowd control as well as prevents all incoming damage, but is also rendered unable to move, declare basic attacks, use summoner spells, and activate items. buys 7 seconds in which every cast is free, and RequiemRequiemRActive: Karthus channels for 3 seconds, then deals magic damage to all targetable enemy champions upon completion. only switches off once 4 of those have gone.
Who has the lane, level by level
1–23–56–10- 1–2Karthus: A one second cooldown against seven
- 3–5Ahri: Charm arrives and he owns no dash
- 6–10Ahri: Spirit Rush crosses the wall
- 11–18Even: Requiem still lands from the other side
- 3CharmLevel 3: 1 second of hold and a 65% slow, on a 12 second clock
- 6RequiemLevel 6: A 3 second channel, 150 mana, and 200 seconds to the next
- 8DefileLevel 8: The aura finally exists: 30 damage a second, and 30 mana to run it
- 9Lay WasteLevel 9: A fully ranked Lay Waste deals 240 to an isolated target
- 9Orb of DeceptionLevel 9: 140 out as magic damage, 140 back as true, on one cast
The numbers, head to head
AhriKarthusPoke at rank 1
His blast returns every second, her orb every seven.
Slow against charm, rank 1
One second of charm is enough to void a 150 mana channel.
The 3 second channel against the escape
A living Karthus can lose the channel to CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds.. Death DefiedDeath DefiedPassiveInnate: Upon taking fatal damage, Karthus enters a zombie state for 7 seconds, during which he can cast his abilities at no cost. If Defile has been learned, it will remain toggled on for Death Defied's entire duration. Requiem becomes disabled after 4 seconds of the duration have elapsed. While under this state, Karthus becomes untargetable and immune to crowd control as well as prevents all incoming damage, but is also rendered unable to move, declare basic attacks, use summoner spells, and activate items. makes him immune to that interruption.
Health at level 6, before items
840The bars are identical, so it comes down to Spirit RushSpirit RushRActive: Ahri dashes to the target location and then fires 3 essence bolts at nearby enemies, prioritizing champions, dealing magic damage. Spirit Rush can be recast up to 2 more times within 10 seconds. Recast: Ahri mimics the first cast's effects. against a wall and a toggle.
Each main at its fifth rank
Both figures need the final skill rank; 
Lay WasteLay WasteQActive: Karthus conjures a blast at the target location that detonates after 0.5 seconds, granting sight of the area and dealing magic damage to all enemies within, doubled when only one target is struck. doubles only when Ahri is the sole target.
Reach, from above
Ahri
Karthus
Rings are ranges in game units, both radars on one scale. Abilities wear their icon, the basic attack wears the champion’s own face; the dashed ring wearing the opponent’s face is their longest reach.
The item race
Ahri
3100gThe 20% amplifier holds for 4 seconds, and Karthus has no dash to spend those 4 seconds leaving.
1100gUse the movement speed to leave Lay Waste before its half-second detonation; magic penetration helps the follow-up.
2560gRequiem cannot be dodged by standing further away, and 45 magic resist is what shrinks it instead.
3260gRequiem only bills champions it can target, so the hourglass has to be running when the channel ends.
Karthus
1200gDefile bills him every second it is on, and the level-up refill hands back 200 mana over 8 seconds.
2800gWhether he survives the Charm rotation at all is a question of 450 health.
- 1100g
Sidestepping Charm keeps Karthus free to cast; the extra movement matters before Ahri closes for Fox-fire.
- 3260g
Cast it before Charm lands rather than after, since 2.5 seconds outlasts any hold she owns.
Play it as Ahri
- 1Throw CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds. from the side of the lane, where no minion is standing on the line between the two of you.
- 2Do not trade through Wall of PainWall of PainWActive: Karthus erects a wall of pain at the target location perpendicular to his facing that lasts 5 seconds, granting sight around its pillars and center. Enemies that touch the wall are inflicted with magic penetration and become slowed for 5 seconds, decaying over the duration. This can affect enemies only once per cast.: at rank 1 it slows 40% for 5 seconds and adds magic penetration to everything he throws after.
- 3Fight him from 875 and further out, where Lay WasteLay WasteQActive: Karthus conjures a blast at the target location that detonates after 0.5 seconds, granting sight of the area and dealing magic damage to all enemies within, doubled when only one target is struck. stops and CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds. still has 100 units to spare.
Play it as Karthus
- 1Channel RequiemRequiemRActive: Karthus channels for 3 seconds, then deals magic damage to all targetable enemy champions upon completion. out of CharmCharmEActive: Ahri blows forth a kiss in the target direction that deals magic damage to the first enemy hit, charming and slowing them by 65% for a duration. Charmed enemies take 20% increased damage from Ahri for 6 seconds. reach while alive; during Death DefiedDeath DefiedPassiveInnate: Upon taking fatal damage, Karthus enters a zombie state for 7 seconds, during which he can cast his abilities at no cost. If Defile has been learned, it will remain toggled on for Death Defied's entire duration. Requiem becomes disabled after 4 seconds of the duration have elapsed. While under this state, Karthus becomes untargetable and immune to crowd control as well as prevents all incoming damage, but is also rendered unable to move, declare basic attacks, use summoner spells, and activate items., start it before the fourth second passes.
- 2Toggle
DefileDefileEPassive: Karthus restores mana whenever he kills an enemy. This passive is disabled when Defile is toggled on. Toggle: Karthus surrounds himself in a necrotic aura that deals magic damage every second to all nearby enemies. Toggling Defile off triggers a final tick of damage. Defile is toggled off automatically if Karthus becomes unable to pay its mana cost. off the moment nothing stands inside 550; it bills 30 mana at rank 1 either way. - 3Aim Lay WasteLay WasteQActive: Karthus conjures a blast at the target location that detonates after 0.5 seconds, granting sight of the area and dealing magic damage to all enemies within, doubled when only one target is struck. where only Ahri stands, because a single target in the blast doubles it to 240 at rank 5.
The kits at a glance
Ahri
Full abilities- Essence Theft
- Orb of Deception
- Fox-fire
- Charm
- Spirit Rush
Karthus
Full abilities- Death Defied
- Lay Waste
- Wall of Pain
- Defile
- Requiem
Base stats, side by side
| Stat | Ahri | Karthus |
|---|---|---|
| Health | 440 (+80) | 465 (+75) |
| HP regen | 0.9 (+0.09) | 1.21 (+0.11) |
| Mana | 280 (+50) | 331 (+61) |
| Attack damage | 53 (+3) | 45.45 (+3.25) |
| Armor | 18.5 (+3.5) | 18.5 (+3.5) |
| Magic resist | 30 | 30 |
| Attack speed | 0.668 (+2) | 0.625 (+2.11) |
| Move speed | 330 | 335 |
| Attack range | 550 | 450 |
Level-1 values with per-level growth in parentheses, read from the Classic client and re-checked against it on every update.
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