At first, Hello!
This is my first guide and I hope you'll be successful if you try this build.

Sejuani is just a tank. She's freezin' you and you can do nothing ^^.
She's a AP-tank with much CC. She gotta AOE stun and slows with her Q and her autoattacks.
You can initiate fights with her or give you team the advantage with her ultimate skill.

shortcuts I used in this Guide.

CC= Crowd Control ( Debuffs like Slow , Stun, knocked back etc.)
AP= Abillity Power
AOE= Area-Of-Effect
AD= Attack Damage
DMG= damage

Watch at the enemies!
Are they playing more on AD or more on AP?
You can buy thornmail against ADs and Force of Nature( Build includes it) against AP.
For dealing more DMG you should buy Abyssal Scepter , Rylais Crystal Scepter or both! ^^

Q or R to initiate -> activate W -> press E for more slow if they run away

The W deals lots of damage over time if you stay near the enemy. It makes her so powerful.
Her ganks a great, the target can't run away if you throw the ultimate after them^^

Look at your positioning. It's very important cause you have to stand near the enemies to be full efficient with the slow.
Autoattack-> Move forward -> Autoattack and do it like this. Everytime!

What I want to tell you NOW is important!
THIS GUIDE IS FOR THOSE WHO WANT TO GO TOP OR JUNGLE
that means you can take smite and ghost/flash for the jungle or Flash/ghost and exhaust/heal/teleport!

Hope this guide was good enough for you!

Bye

DarkHazard