Sivir's Boomerang Blade returns to her after reaching the max range, so you can shift position to hit enemies who would otherwise have evaded it.
Try saving Spell Shield for enemy abilities that can disable you such as stuns and roots.
Ricochet resets Sivir's basic attack timer on activation, so activating this immediately after landing a normal basic attack will maximize damage output.
When Kayn is in terrain near you, you will get a visual warning on the edge of the terrain he's in.
Umbral Trespass requires Kayn to damage a target first. Try to dodge Blade's Reach to deny him a long range cast of Umbral Trespass.
Damage Kayn while he's in Shadow Step to shorten its duration, or apply hard crowd control (stun, charm, knockup, etc) to end Shadow Step immediately.
The stats shown here underscore some vital Sivir against Kayn counter statistics that may help you explain the differences between the two. As an example, Sivir’s KDA ratio ([kills + assists] / deaths) of NaN is better than Kayn’s ratio of NaN, showing that Sivir may be more central to her team's team fighting effectiveness than Kayn..
Sivir normally has a slightly smaller longest killing spree than her enemy does. On average, she takes less damage than Kayn. This commonly reflects differing health capacities, but it can also indicate that the one champ has less mobility and thus is not able to kite away from further damage when engaged or poked.
Both League of Legends champions are great champions. Both champs have their strengths, weaknesses, and counters. In the game's current meta, Sivir usually fairs equally well when taking on Kayn, with a 49.4% win rate. Thus, Sivir makes an ok counter to Kayn.
While Sivir does have a lower win rate than Kayn, when they face off with one another, Sivir also has a much lower level of difficulty that makes her a less time consuming champion to develop with. You still need to be cautious when picking Sivir into Kayn.
Additionally, Sivir also has only a small amount of utility and CC, a similar amount to Kayn. This often makes her just as valuable during team fights, especially when facing champions with a ton of burst damage.
While there is not a single best champion in League of Legends, in Sivir vs Kayn matchups, Kayn is the better champ with a similar win rate, less champion complexity, and a similar amount of utility to help out your allied champions during teamfights.
Sivir is a somewhat poor counter to Kayn. You will do well by focussing your play on increasing your gold and cs and destroying objectives. If you are able to do that, you should do very well as Sivir against Kayn.
If you would like to learn all of the intricacies of Sivir to counter Kayn during both the lane and mid / late game phases of League of Legends, you should keep reading to gather a few extra tips and tricks for this matchup. If you listen to the build and tips shown here, you will grow your win rate by a lot and be closer to League of Legends pro players.
Sivir typically gets much more CS relative to Kayn. Champs who typically don't earn many minion kills typically don't require much CS to be effective, such as support champions. These kinds of champions are able to scale properly off of their abilities and first items alone. Yet, champions with a lot of CS, such as hyper-carries, usually require several high cost items to be effective. In either situation, try to exceed the numbers displayed here to do well.
The top items to use in your Sivir versus Kayn build include Kraken Slayer, Immortal Shieldbow, and Navori Quickblades. When Sivir incorporated at least these three pieces in her build, she did much better versus Kayn than with many other typical builds. In fact, Sivir boasted an average winrate of 49.4% when playing against Kayn with this counter build.
To have the best chance of coming out on top against Kayn as Sivir, you should use the Lethal Tempo, Presence of Mind, Legend: Bloodline, Coup de Grace, Biscuit Delivery, and Magical Footwear runes from the Precision and Inspiration rune sets. Out of all the rune combinations players used for Sivir vs Kayn counter picks, this composite of runes yielded the best win rate. Moreover, these runes provided a 49.4% winrate overall.
By default, tips, stats, and builds on how to beat Kayn as Sivir are displayed for all ranked divisions combined. To scope the stats and builds to a specific skill level, you can use the selection menu located earlier on the page.