Please dont say that this biuld sucks. Whitout trying. Later i will post print screen, videos for explain how 2 play Sejuani correctly. To play Sejuani u need 2 now how 2 engage correctly have time 2 engage, and u need 2 analyse the diferents situations for a 1vs1.

Shes a good solo or jungle, i will post later the jungle route,masteries and items.

If u play her for first or second time, give time to you really now what can u do and how 2 do it rigth.

The last items can change depending of your enemies team.

The way 2 combo:
Shurelya's + Arctic Assault + Northern Winds + Permafrost + Glacial Prison + Randium
Shurelya's + Glacial Prison + Arctic Assault + Northern Winds + Permafrost + + Randium

And if Glacial Prison is on CD:
Shurelya's + Randium + Arctic Assault + Northern Winds + Permafrost

Dominate top lane:
[*] Ignite
[*] Heal

If u dont fell 2 save on heal use Exhaust or even Flash but its not needed beacause of the items u will have and your Arctic Assault its quite good enough 2 scape from possible ganks.

Level Arctic Assault on level 1 then only at 13 to up.
Northern Winds level at 2,4,6,8 and 10.
Permafrost level at 3,5,7,9, and 12.
Glacial Prison 6,11 and 16.

Shes that champion that brokes a team figth Glacial Prison, Shurelya's and Randium are really needed if u have all in CD dont try 2 engage. Sejuani its great to instant kill AP ad AD carry and Glacial Prison, Shurelya's and Randium are the best of Sejuani.

Northern Winds its great 2 farm , but care whit the mana that u waste because u can be force to 1vs1 or 2vs1 and without mana u will not deal damge at all. At mid game u can farm better the mana will not end in 2 or 3 combos. So u can fell free to waste mana after mid game until the late.

Pros:
Good amout of hp and damage.
Good to hold top lane and problably win the lane.
Good farmer.
Good team engager.
Good at team figth to split the team.
If u pick her, people will think that u are going jungle so the top lane its hard to have magic resist and they buy only magic resist at levels 8 to up.

Cons:
I still dont have 2 much to say about this, i prefer lane than jungle.
Shes good jungler and ganker. But i can dominate top lanne because u push hard and u can counter jungle or gank mid. Shes Hard 2 die and this build make you do damage and even if top lane its warded just use Glacial Prison for your jungler have time 2 come.

Sejuani its bad whithout the 3 Skills up, dont force 1vs1 or 2vs1 if u have on CD your abilities.

Later will post on ranked games.