again, AP sejauni doesnt work. even with 250 AP, it barealy benefits sejauni. 250 AP is 25x6 dmg on your W, 100 dmg on your Q, and 125 dmg on your E, and 200 dmg on your ulti. all of which would be blocked by 50-200 MR (depending on who it hit) which would reduce the effective ness of your AP to ~25-50% of the extra damage you think your getting.

unlike someone who benefits from AP, for example, Shen, whose shield and ulti and Q scale off of AP (and a good dam amount too, 70% on Q, 150% ulti, etc etc) sejauni has low AP ratios, and the scaling part of each skill just increases the damage.

really your just building an AP sejauni offtank, with only 2 1/2 tanky items and 2 HP/AP items.

instead, on sejauni, build a frozen mallet, a shurlyys, and a chain vest and negatron cloak, along with some GP/5 items. really the best way to to get tons of HP early on through giant belts/frozen mallet, shurlyas, maybe a warmogs/sunfire cape, and some resistances in the form of atmas (which goes great with frozen mallet, makes you hit hard), randuins, RH, FoN, banshees, QSS, etc etc.

even with just frozen mallot and atmas, sunfire, and FoN, you deal waaaay more damage, and have just as good/better resistances and HP, in the place of RoA, rylais, abyssal, and FH. and it's cheaper

i do understand that most of sejauni's skills are AOE, but lets face it, unless you land a perfect ulti an a bunched up team, and hit them all w/ arctic ***ualt/permafrost, you wont be dealing that much damage. and really, as said above, your only dealing a fraction of that, unless you build voidstaff, etc

sorry for the wall of text xD

Yes, it's true, but all junglers have to gank. If you get some assists, it will help you a lot to complete your build. 15375 gold is a bit much for a tank, but not for a jungler.

I think this is far too expensive a build for someone like Sejuani. She's not going to run around and get 20 kills. She's not Volibear, who can easily tank and carry at the same time. I feel you'd have too slow and squishy of a start with this build, and never really get past the RoA.