This is a little guide for a tanky Sejuani. I builded it myself and think it's good. You will find some problems in this guide, gladly tell me them

Choosed Tier 3, tank runes, that gives armor, magic restistance, health regen and health

Masteries choosen is defencive and really good for tanks.

Movement speed, Armor, health regen, magic recistance and health is what you need for a tank, all those is bought in my guide and also a Atmas Impaler which makes 2% of your maximum health transform to attack damage, and with 4000 health, about 80 attack damage will be good

Choose the W spell as you main attack so your attackers will get damage per second, secondly i recommend upgrade your Q so you can easiely take aggro and also gank.
The E spell is really good to have just to stun them but i dont think its damage is worth.

Flash and Exhaust is really good summoner spells to easy take aggro with flash, and slow your enemy so your allies can kill him easy with exhaust

I really think Sejuani is worth buing if you want a really nice tank!

PROS

* Easy to gank with (Q spell and flash)

* Great AoE (W and E spell)

* Good Farmer (W and E spell)

* Great Tank With Much Health

* Great Slowing Spells

* High Damage Ultimate That Stuns

CONS

* Not very high damage against single units (only ganks). More effective in AoE.

* Easy to get underleveled.. ;(

Sejuani is a good farmer with here W and E spell.