I'm going to explain some of the supposed philosophy behind your choices, then I'm going to try to improve your Sejuani play. Feel free to ignore me when deemed appropriate.

Maxing Arctic Assault first makes you mana-hungry and sets you up as a gank-reliant jungler. This is a gamble, because getting gold and experience from ganks isn't guaranteed. Many people max Flail of the Northern Winds first because it makes the dependable jungle farming quicker and easier.

A longer first Blue buff (from the Runic Affinity mastery) might help her early clears. Your choice is either between 30 extra seconds of Blue buff, or 8% Magic Pen from Arcane Knowledge . 8% magic pen will make 30 MR equal to 27.6, which makes me think the extra 30 seconds of Blue buff more desirable.

Bladed Armor has a nonzero chance to steal buffs you mean to transfer to teammates, most typically your mid laner or marksman, if you decide to tank it for them. How do you protect against this possibility? Furthermore, since all the jungle creeps attack about 0.6 to 0.7 times a second, meaning you'll do about 3-4 damage-per-second to them. Do you think that's worth it?

How often do you buy Liandry's Torment on Sejuani? Do you have a high win percentage with this item? When I do get it, it's often as a last item, and I end up winning the game with it because I surprise the enemy with the amount of damage I do.

What makes you skip over Frozen Heart? Do you ever get it? I rush Glacial Shroud because it boosts her ability to clear the jungle immensely, with Armor, CDR, and Mana. Try it sometime.

How do I prevent counterjungling, especially by Lee Sin, Shaco or Udyr? You mention we should "be careful" with this, but you don't help us figure out how. People don't just know these things, so any specific advice you can give will help.

Good start, but this guide is far from complete.

Notes about this guide;
-Kinda boring to read, no pretty pictures or stuff.
-General lack of information. Explain jungling and jungling paths, how to deal with invades and strong counter junglers etc.
-Add a brief summary about each of your skills in the skill sequence chapter.
-Runes & masteries could be explained better.
-Put the early game & late game chapters in to one chapter called "gameplay" (or whatever fits)
-Mid game chapter?
-More item choices would be nice.

Final verdict: Good guide actually. But I still won't vote. I'm expecting this guide to rise up
after a few key changes (mainly asthetic) are made :3

Personal note: I really like your writing style.

If I helped you, I'd appreciate a +rep :3

It lacks substance as far what you do in the jungle goes about, and there isn't really a lot as far as options on item building.

Maybe expanding on these would grant the guide more wholesome content that better explains how to get to being a successful tank as Sejuani. It otherwise explains the key concepts of being that tank, however.

Never use CDR blues on any champion who isn't Soraka

Thanks for the feedback everyone. I'll see about adding some more text and useful information.

I wouldn't do that

Don't think that's ever worth it.

Ive also seen CDR blues on Seju to keep W up most the time early game, but I'm torn wether to use them or not myself.

Skill-based AD junglers usually take Arp marks and AD quints. Hybrid pen are good for AP junglers. Attack speed on everything else.

That's late damage though, and heavily item-dependent. I think 9/21/0 is pretty fine because she benefits greatly from mpen. Hard to say which is optimal.

Anyway, to clear up that little chestnut on runes:

Attack speed reds are standard on many junglers, including every tank jungler. There is only one jungler in the game who doesn't benefit from attack speed reds - Fiddlesticks. Skill-dependent AD junglers, such as Zed, can take flat AD or even arpen instead.

I get it a lot... but then I generally get fed as **** with Sejuani... I don't know how.

Naut's damage is high as well, but you don't need the 1 ap/lvl nor the 8% mpen for it. 0/21/9 speeds up your jungle significantly. Also, champs like Naut and Seju don't often even get to build Torment. It's fun if you want to but it's not what you were hired for.