Alright, well this will be my first Guide here on MobaFire. I have an annoying habit of checking out people's builds and asking them about it in game, but for once I will be showing my ideas for the world to see.
First off, when this build was uploaded, Sejuani is relatively new, and I will likely tweak it as i begin to narrow in on various combo items that give her different qualities.
I picked up Sejuani as a way to change my game play, I'm normally an AP kind of player, but for some reason this CC tank got my wondering about my skills. (That and a week long losing streak... -.-')
So i picked up Sejuani, threw her into a few games, playing around with the build.
Things i came up with?

Sejuani is a better Jungle, and faster at it than most champs I've tried. Secondly, once initiated, without a form of blink or stun, Sejuani and Company can be very difficult to escape.
So this build focuses around keeping Sejuani where she likes it, in the middle of the fight, CCing the most valuable target!

Greater Mark of Armor
This is a low level rune as a mark, but adding to Sejuani 's overall toughness is welcomed. You can trade these for AD Penetration, or Dual Penetration marks if you feel the need for more damage.
Greater Seal of Health
Now this is a rune for Sejuani It gives her bonus health, which similar to Volibear triggers the passive bonus on her most powerful ability. Her Northern Winds!
Greater Glyph of Magic Resist
Much like any tank, you can't simply invest in only a single defensive stat, otherwise in a bad match up, your preparation will have been for nothing. These runes give you the bonus of being able to take hits from AP champions, earlier on.
Greater Quintessence of Health
MORE HEALTH! As stated above, Sejuani drives her strongest asset, her Health, into her power, giving bonus Health makes her more of a tank, and increases her sustain and damage output.


If you'd like you can go Full HP runes on Sejuani as a contrast, but i find the bonuses applied from the other HP types, isn't enough to account for the loss in defenses.

The Key to Sejuani is health. I cannot state this enough. This adds to her survive-ability, and makes her Northern Winds a very powerful crowd damage effect.

Your role as a Jungler however has you making the most obvious choice. Cloth Armor and 5 health potions. Do not get me wrong this helps you build into your Ninja Tabi Later, so they are a strong choice.
If your not feeling up for it you can always start with a Regrowth Pendant or Ruby Crystal if you opted out for greed masteries.

From here its non stop JUNGLE GANK into Warmogs Armor. In the mean time you may feel the need to return home, when you do grab your Ninja Tabi and Giants Belt and head right back out into the fields of Justice.

The rest of the build adds to Sejuani 's friendliness in lane. You can choose any order to build these items, but i prefer this order that gives clean progression.

Shurelya's Battlesong Gives you CR, and H M regeneration, and if needed an active for Chases and Escapes. If you haven't fully built it yet the Nomad's Medallion Is a good shortcut preference, the extra income can be UNCANNY.

At this point I get torn, go for Frozen Mallet If your dominating and have huge sums of cash, or Sunfire Aegis if you need the survive-ability and the extra ticks of damage it adds into a team fight/chase. Get both for sure though.
Finally we come to Randuin's Omen This is the icing on the cake, armor, health regen, and a cool active effect that once again, SLOWS. The benificall chance of slow FURTHER adds to Sejuani 's CC capabilities.

OPTION

Mercury's Treads
A lot of CC on the enemy team merits attention! If your getting focused too hard or having trouble catching a few pesky carries, take these boots, tenacity can lend itself to avoiding more damage than you think.

Eleisa's Miracle
This gives your Sejuani tenacity, as described above, for avoiding CC used on you. Its got good regen and builds off Philosopher's Stone, so extra income could lend itself to other items to make up for the loss of Extra health.

Flash
Sejuani 's main escape is her Arctic Assault as it can Jump over walls of almost any size of its Line. However most of the time you must be skitting along the larger walls for this to happen in certain cases. Along with its heavy Cooldown and the fact that MOST fights will be Initiated with this ability, means it won't likely be available for that needed escape. SO thats why we take flash, emergency teleport GO!

Smite
Jungler tool, handy for getting those pesky last hits on Dragon or baron too. Feel free to throw this out any time, just to kill a minion, as one less minion, is one less minion. Oh and 10 additional gold on use too from your masteries!

OPTION

Cleanse
CC getting you down? Well no more with Cleanse around. This is a tough option to go since most of the time you do no know what types of champions your up against. However if your confident in your escape and tank abilities, this spell might just be for you!

Your starting Sejuani off with
Smite Cloth Armor and 5 Health Potion

From here head on up to the ancient golem. Get someone with range to watch your jungle then leash for you. Take out the golem with Smite and your Northern Winds. From here you level into your Arctic Assault and bum rush wolves with it, then use your Norther Winds again. This will make killing any jungle minions easy job. After wraiths next its up to you to try going against the lizard elder or into Big and Little Golem. I prefer B L golems as they are quicker for level 3. Get your Permafrost and now this is where it gets interesting.

This is where the ganking will likely begin. If first blood has not been drawn, head to mid or bottom lane (Whichever is weaker or needs help). Inform your teammates about letting the enemy push in, Sejuani isn't quite ready for tower damage yet.
If first blood has been drawn, try to keep up your jungle until aid is called, or you see a viable gank on your travels.
Sejuani doesn't need the kills from these assaults, but sometimes with Northern Winds they are unavoidable.
From here you can rinse and repeat until you get Glacial Prison. Its at this point Sejuani can, "IF" needed, head into the lanes as a wall for the enemy to try and break. However keeping her as a surprise or held back a bit can yield rewards.

Sejuani 's Arctic Assault is a tool for

Escaping: Over walls, or away from enemies and skill shots.

Engaging: If Sejuani is unseen, this attack can come very fast and slows all enemies affected. From here pick your target, Ping if needed, and let you and your teammates rail into them.

Catching: Sometimes keep this ability ready for when an enemy flashes or uses a skill to escape, catching them again can lead you to easy kills, when they otherwise may have escaped.

Sejuani 's Northern Winds is a great Farm tool if used directly after Arctic Assault, as the damage that ramps up is HUGE with large amounts of bonus health. Don't under estimate its graphic either, its damage is dealt at a surprisingly larger range then its image. about the same distance as Sunfire Aegis 's passive.

Sejuani 's biggest asset, is her health. Much like any tank she uses it to stay in the fight longer, and similar to Volibear she turns it into damage for her abilities. As a result Sejuani when fed, can tank 2-4 champions, not for kills, but for stalls. When doing this you want to head in and out of their engaging range, just to draw them out. Arctic Assault after they used a stun or slow can mean an easy set up for Northern Winds damage. However if your doing this to stall, don't over commit. You want to be doing damage, not committing suicide.

A final note,
Sejuani is a new champion.
I personally don't find her very over powered, but if played right and fed well, she can become a HUGE nuisance to enemy teams.
As a result watch out who your engaging and how they are reacting. Hitting the same target over and over again can lead to not being able to gauge the strength of the rest of the team.
You want to test the waters during those early ganks, see who you can and can't tank or defeat in a drawn out battle. Her slow is her greatest tool, and her health is her greatest asset.

Good luck Summoners, my Freljord be kind to you.


IMAGE CREDITS TO Riot Games and its associates.