Jungle Sejuani has a powerful skill set for ganking during the laning phase, especially once she gets her ulti.

This is a great build to allow you to jungle safely, gank early, as well as rush your build regardless of how well the ganks go or not.

PROS:
Consistent/Hard CC.
Effective ganker.
Great initiations as well as escapes.
A well placed ultimate can landslide a teamfight in your favor.
Good Farmer.
Good early game damage, and consistent late game DPS.

CONS:
Mana hungry early-mid game.
Semi-slow jungle early game.
Jungle relies heavily on mana-use.
Low damage output mid game.
Somewhat reliant on teammates being skilled when it comes to her ganking during the laning phase.
No true defensive skills (IE: Shields, armor/mr/hp restore steroids).

Flat Armor Runes to insure you stay healthy throughout the jungle, and to make up for the GP10 Item early buys.

Flat MR Runes to provide you with a little extra MR that the item build doesn't supply much of, as well as safety when ganking AP carries early on.

GP10 Runes because 5gp10 between runes and masteries is great for a jungler who leaves the jungle often to gank, and getting items earlier on will prove more effective then what most Quints have to offer.

I prefer the 0/17/14 build for a lot of Tanky/Gank effective junglers because it gives you the sustainability you need to clear the jungle, Tank late game, and some Movement speed in BOTH Defense and Utility trees for much more effective ganks.

This bonus Movement Speed is key on Sejuani due to the effectiveness of her passive, especially considering it's significant Synergy with her other abilities.

This build also gives you bonuses to bother of your summoner spells, as well as additional GP10/Increased buff duration, which is very necessary for Sejuani's early game ganking/jungling due to her lack of mana efficiency.

Rushing the GP10 items is key to getting some powerful midgame items, because regardless of whether you pick up kills/assist on ganks or don't, you will be ready to start tanking in teamfights when the time comes.

Depending on the enemy carries, you may want to purchase some of the later items in a different order, but Mercs/Aegis/Frozen Heart should ALWAYS be your priority.

This is because CC directly counters Sejuani's most effective card, Consistent/Hard CC. Aegis gives you all around stats at a low cost for an effective mid game, and Frozen Heart gives you some necessary mana, a ton of armor, and most importantly, it weakens enemy AD carries as well as a nice chunk of CDR which means more Q's for Chasing/Escaping, More DPS with W(which synergizes very well with sunfire later on), More slows with E, and more of Sejuani's Beautiful Ultimate.

I've found this skill sequencing to be most effective.

Max W first because it's good for her jungling, teamfight damage output, as well as clearing minion waves quickly.

Q second because it's a great ability for escaping ganks, ganking, applying frost to multiple enemy champions, and suprisingly good burst damage early-mid game for helping your allies pick up kills.

E even though the slow is great for ganks, I max E last because I rely on it the least throughout most of the game. The slow is great for after an enemy manages to slip away, and for slowing enemies that are chasing your low-hp carries.

W and Q being maxed first is due to Sejuani's skillset making her more of a bully champion. She can rush in and out of fights/ganks with ease, and when she picks a target you want to do as much damage to them as possible while they're desperately run away.

R - Sejuani's ultimate is incredibly powerful, it can pass over walls, save your carries, screw over the enemies carries, and can freeze multiple targets at once. It's somewhat hard for enemies to dodge too, thanks to the fact that it sets off at max range, even when it doesn't directly hit an enemy.

Learn to utilize your ultimate to it's max potential during teamfights, try to work alongside your ally champions who have AOE abilities, especially if they have an AOE Ultimate as well.

While it's a great initiating tool, I find it best to save it for mid-teamfight when multiple melee champs or casters get too clustered and put out tons of damage, Sej's ultimate can easily turn a teamfight in your favor.

Although Sejuani is played as a jungler in this build, I don't focus on the jungle too much unless there is nothing to gank.

Don't spend too much time farming, because her powerful skillset for ganking/pushing lanes makes it very very rewarding to gank as often as possible and then push towers early in the game.

Wolves, blue, wraiths, red, look for an enemy pushed past the midpoint of their lane, attempt to gank, or proceed to wolves/wraiths again.

Sejuani's jungle relies on mana a lot, so it's important that you keep up on blues/gank the enemy with blue whenever you can. Mid-late game blue isn't an absolute necessity but still great for her, especially the CDR.

I hope you enjoy this build, as well as discover just how great of a champion Sejuani really is as a tanky jungler.

Any feedback would very much be appreciated.