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.
Dodging Arctic Assault and Glacial Prison can give you a huge advantage.
Focus on avoiding the second swing of Winter's Wrath which carries the brunt of the damage.
Melee enemies can also stack Frost for Sejuani, be very careful around them.
The stat comparisons shown on this page underscore some influential Sivir versus Sejuani matchup statistics that may help us realize the differences between the two. As an example, Sivir’s KDA ratio ([kills + assists] / deaths) of NaN is greater than Sejuani’s ratio of NaN, showing that Sivir may be more central to her team's team fighting capacity than Sejuani..
Sivir often has a slightly larger longest kill spree than her opponent does. Commonly, she receives less damage than Sejuani. This typically indicates different amounts of tankyness, yet it can also indicate that the champion with more HP has less agility and thus is not able to escape further harm when engaged or poked.
Both LoL champs are great champions. Both champs have their strengths, weaknesses, and counters. In League's current meta, Sivir usually wins when trying to fight Sejuani, with a 53.8% win rate. Thus, Sivir makes a great counter to Sejuani.
While Sivir does have a higher winrate compared to Sejuani, when they face off with one another, Sivir also has a greater learning curve that makes her a more complex champion to pick up and master. You don't need to be too worried when picking Sivir into Sejuani.
Furthermore, Sivir also has almost no amount of CC and other utility, a similar amount to Sejuani. This makes her just as valuable during teamfights, especially when facing champions with a ton of burst damage.
While there isn't a single best champion in League of Legends, in Sivir vs Sejuani matchups, Sivir is the better champion with a noticably higher win rate, similar champion depth, and a similar amount of utility to help out your allied champions during late stage team fights.
Sivir is a great counter to Sejuani. You will do well by focussing your actions on increasing your gold and cs and clearing objectives. If you can do that, you should do very well as Sivir against Sejuani.
To truly master Sivir to counter Sejuani during both the laning and mid / late game phases of League of Legends, you should keep reading to pick up a few extra tricks and insights into this matchup. If you listen to the build and suggestions shown above, you will grow your win rate significantly and be that much closer to League of Legends pro players.
Sivir often gets much more CS relative to Sejuani. Champions who typically don't earn many minion kills typically don't require much CS to be valuable teammates, such as supports. These kinds of champions are capable of scaling well off of their skills, stats, and first items alone. Yet, champs with a lot of CS, such as hyper-carries, often need a lot of items to be effective. In either situation, try to exceed the values shown here to do well.
The ideal items to use in your Sivir versus Sejuani build consist of Bloodthirster, Kraken Slayer, and Navori Quickblades. When Sivir combined at least these three items in her build, she performed significantly better when fighting Sejuani than with many other typical builds. In fact, Sivir had an average winrate of 53.8% battling Sejuani with this build.
To have the greatest likelihood of coming out on top against Sejuani 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. Of all the rune combinations players picked for Sivir vs Sejuani counterpicks, this combination of runes yielded the greatest win rate. In fact, these runes gave a 53.8% winrate overall.
By default, tips, statistics, and builds on how to beat Sejuani as Sivir are presented for all skill levels combined. If you would like to scope the stats and builds to a particular skill level, you can use the selection menu earlier on the page.