WORK IN PROGRESS
This is my first guide so before you downvote it, read the whole thing. Give it a chance man. Also leave some constuctive criticism please.

Now that that unpleasantness is over with, welcome to jungle nasus guide. I've played a total of one (edit 2 both wins nuck my suts) ranked games with jungle nasus, making me the best jungle nasus na. (On par with diamondprox) Thousands of people asked me to make a guide detailing my amazing jungle nasus so I did. But in all seriousness I'm being super serious. I promise.

Nasus just got buffed so everyone's like, "LOLOLOL NASUS OP TIEM TO PLAH HIM IN RANKED LOLOLOLOL" Then they first pick nasus top and get dunked by someone like rumble or something. Nasus doesn't win a lot of lanes, so how can he farm without nasty other champions hurting him? Simple, play jungle. His ganks aren't too bad, so don't worry bout that. Also he's a GIANT ****ING DOG SO BOOM B**** GET OUT THE WAY.

Also i'm gold

Move speed Quints - So you can move faster. Duh. But seriously, it'll help you catch up to those pesky carries who try to kite you all day.

Attack speed marks- These can be subbbed out for attack damage marks, since your q is an attack reset, but for seriously this helps your speed early.

Armor seals - Helps you be tank. No need for health, you have your ult, and your build has lotsa health.

Mr Glyphs- More tanky stuff. No other glyphs really necessary.

- I like ghost on nasus, it helps you repeatedly whack people, which will be most of your damage late.

Smite - For jungling. Duh.

Flash - Eh, it'll help you get one or two qs off, but ghost is so much better against slightly faster guys.

Ignite - you really need ghost or flash or you'll get kited fo days.

Every other summoner spell- ^

9-21-0.
Offense Tree
So you need this stuff to help you jungle stuff. The summoner spell thing for a better ghost, the other things for faster jungle clear. You don't really need to put more than this in your tree cuz nearly all of your damage will come from spamming q. Also take attack speed mastery over ad at level 18 because attack speed is better for early jungle.

Defense tree:
Basic defense tree jungling masteries, creep defense stuff, health masteries, armor stuff, so you can be a tank.

Utility tree: You can put stuff in movement speed and mana and buff duration, but I think that putting stuff in offense tree much better.

5 everytime. If you want to be a good guy and buy a , it'll hurt your jungle but whatevs.and should be your first buy to help with jungle, and being faster. Trust meh, being faster = good. Anways, you may want to get before tier two boots, becausethey aren't really that super important to rush. and are super duper important on nasus. Unless your support is tryhard and get , rush these two items. They are so good for your team,gives so much good stats and mitigates so much damage,buy them as fast as you can. Always. After that, you should build based on what the enemy has. One might conclude, gives bonus health regen per health, nasus gains a lot of bonus health, plus you build items that give health, therefore buy warmog's quickleh. However, and don't give a lot of armor and mr, so randuins or might be better. Frozen heart, sunfire cape, and spirit of the ancient golem may also be good picks. If you're like, super dunking the enemy team, you can build but I wouldn't recommend it because it cost so much cash money.
*IMPORTANT* It's literally impossible to give an exact build for any given champion, due to the fact that you have to build according to what the other guys pick. There's no one build for every single game. This is an extremely important concept. You might be able to get away with this on an ad carry, but for every other champion, you have to build according to the enemy team comp or else you will be incredibly disadvantaged. (ie* against an all ad team with like talon mid or something, banshee's is a really, really bad pick)

Passive Soul Eater- give bonus lifesteal
This ^ is really good in jungle, and when you're chowing down on the enemy adc. Also works with siphoning strike which is also good. Rewards you for hitting people, which you will do alot.

Q Siphoning Strike - Does bonus damage + extra damage for everytime you last hit a creep.
It rewards you for last hitting. This skill scales so so so so so well into late game. Also, it reinforces farming, which, although you need to spend some time ganking, happens alot in nasus jungle.

W Wither Movement and attack spee Slows alot. Slow gets greater throughout the duration.
This skill basically stops your target in their tracks. Second best slow in game (thresh ult), super amazing late game.

ESpirit Fire AKA (The Circle of life and death) Deals damage, then more damage over time. Also reduces armor.
Armor reduction is pretty good, max this first for jungle clear. Not incredibly helpful late game, but it does a decent amount of damage in an aoe early.

RFury of the Sands You turn into a giant dog, gaining max health and dealing damage in an aoe around you, also gain attack damage equal to a percentage of damage done. Also skills range increases.
This is like the juggernaut mode. Wither range increases is great, siphoning strike range increase great, damage great, health great. This ult makes you "God" for the most part. Use this when diving into the enemy team so you don't instantly melt.

I mainly go e > q > w > r because the e is imperative for clear time. I do q before w for the cooldown reduction on the q so you can farm more jungle creeps to make your q do tons of damage.

The jungle route is relatively simple, start wolves, then blue, then wraiths, then red, then golems, then rinse and repeat. You can skip golems if you want, they're a pain in the ***. Also, you should smite blue and golems.

Ganks - Although you put only one point in w early, it still is a decent slow. However, you've got to be careful when ganking, because they aren't the best in the world. Make smart choices, don't run over wards unless the other lane is super pushed, and try to coordinate a lane gank. The most important thing is having map awareness. Be aware of where the enemy jungler is, as well as any roaming solo lanes.

Teamfights- Generally, Nasus runs into the enemy team and wither the enemy ad carry and tries to be as annoying as possible with his q and ult while the rest of the ally team cleans up. However, if you fall behind, you might wanna just stick to withering whoever tries to kill our ad carry, and taking them down quick. Remember, nasus scales into late game phenomenally. So if you have a bad start just try to farm and build tanky as quick as possible.

So that's it. Play at least one normal game before playing nasus in ranked. Also don't forget to comment and upvote plox!! :)