Hello,
Welcome to my Sejuani build.
This is my first build on MOBAfire so please let me know what you think on the comments!

Passive: - Sejuani's basic attacks apply Frost, reducing enemy Movement Speed by 10% for 3 seconds.

Q-> Artic Assault - Sejuani charges forward to deal magic damage and
apply Frost to enemies. Sejuani stops upon colliding with an enemy champion.

*Use this to apply your passive to a large number of creeps/players. Always open the teamfights
with this skill.

W-> Northern Winds - Sejuani summons an arctic storm around her which deals magic damage to nearby enemies every second. Damage is increased against enemies affected by Frost or Permafrost.

* After you land your Q this will deal extra damage! Stacked with Sunfirecape will melt your enemies!

E-> Permafrost - Sejuani converts Frost on nearby enemies to Permafrost, dealing magic damage and increasing the Movement Speed reduction dramatically.

* This is your main spell! Again your 1,2,3 combo is Q-W-E. After you land Q this will slow your opponents even more! But remember to use your W before for the extra damage.

R-> Glacial Prison - Sejuani throws her weapon, stunning the first enemy champion hit. Nearby enemies are stunned for a shorter duration. All targets take magic damage and are affected by Frost.

* This spell is great! Aoe stun? Yes please! Remember DO NOT START with this spell unless you are sure you/your team will kill your target! In my opinion this spell have a big cooldown so be sure to not to waste it.

Pros:

Can easily gank
Amazing Slow
Great Farmer/jungler

Cons:

Ulti have long CD
Your damage is not that great

Route:
Wolves > Blue > Wraiths > *check the lanes. if you can gank do red ASAP and let your team mates know u are going to gank* > Golems > Base > Red

Tips:
-When you want to clear out a wave of minions just use Q (try to hit them all) turn W on and then hit E. This works on the jungle too of course.

- When ganking always ask if it is there any wards or ask your support to keep an eye on the other support items or even check it yourself by clicking TAB if you see the support with wards click on him to check how many..when you want to gank check it again to see if he placed any of them.

- ALWAYS try to use your ult in the end. Because if you open a fight with your ult they just flash away .. so I recommend: Q->W->E just like you do when you are jungling/farming waves. Remember to always attack them with melee to apply your slow. If you see them fleeing use your Ult. Don't be afraid to tower dive because you have a huge HP pool. Just let your parther know by ALT + clicking on the target.

Since your W scales with your MAX HP this build is aimmed to get the most damage out of it, while having a nice amount of armor and mag. resist.

I have seen a few Sejuani builds and most of them go either full tank or atmogs or even trinity!
I think that's not the right way to build her. To be honest I feel like she's like Gragas, Nunu,Etc.


Why not atmogs/trinity?
Her skills scale with AP and HP..I think it's a waste of items.


Is there any other items that work good on her?
Yes there are:

Warmog + HP = Moar tanky & W does moar damage

Rylais Your W will slow them too. You get AP and HP from it so it's cool. If you don't want to build RoA this is a good item too.

Shurelya's +HP! This is also a good item on Sejuani but I'd rather leave it for mov. speed dependent champs or support.

Etc.

Why not go full tank?
You can. Sure. But you will do no damage at all. This depends on your team too:
If you have enough damage on your team why not going full tank?

I take the basic spells for jungling, but as long you take Smite it's fine. Every player should pick the spells that best suit their play style.

Sejuani is an amazing champion.
She is an amazing ganker, a nice tank and have good CC. I haven't seen much people playing her I think she's being underestimated. So please give her a try and see it for yourself.

Thanks for reading!