Hey.
I wrote this guide because I havn't seen many Azirs at all ( am only one playing him?).
I am quite successfull with him so I decided to write this guide. From what i have seen so far the build and runes I use work out best for him.

If you are interested in learning him, then please proceed.
I hope it helps you and maybe I will see some more Azirs out there :)

I think I wont have to say why to use flash.

As my second summoner i use exhaust, mainly to hold them longer in my Sand solderis for them to deal damage and to prevent them bursting me.

Ok, first of all i think many may ask why no nashors. In my opinion nashors is not good on Azir. He gets cd and attack speed but he gets cd nonetheless and in the end he has enoug hattack speed. Nashors passiv has no use, because he mainly attacks with his soldiers which count as spell and don't proc nashors passiv. There are better items for Nashors.

First Item:
So the first item to complete is either Morellonomicon against AD / normal or Athenes which you build into heavy AP. Both give 20% cdr and good ap and mana reg. I usually get it before 2nd tier shoes.

Second Item:
Ok by now you should have either Morellonomicon or Athenes. Afterwards you get as seconds complete items ionian boots. With this you get max cdr and thanks to azirs passiv 50% attack speed.

Third Item:
Here I get most of the time a void staff. Good AP and most of all the magic penetration.

Fourth Item:
Rabadons. His sand soldiers scale pretty well with ap but no needd to rush ap too early because he deals good damage nonetheless and has good survivability.

Fifth Item:
Either Rylais or Liandrys. In my opinion Rylais is better because of the slow your sand soldiers proc with every auto attack + the health you get.

Liandrys gives health too but is more the offensive variety. It gives magic penetration and the passiv from Liandrys.

Last Item:
Most of the time the only item needed now is a Guardian Angel. You got good health thanks to your runes and items and now only need some kind of insurance in case you really die.
But you should be able to hold enemies pretty much of and kill them by now.

First Max: Ultimate
Well like every champion his ultimate should be prioritized over every other skill.
It is a extremly strategical skill. It can be used to protect your adc in teamfights when fighting in jungle or do save your teammates from assassins to killing enemies with it. It is a really important spell for Azir an most of all for his team. Use it visely.

Second Max: Q
Ok the real skill you should max first is Q. It is one of his most used and most important spells. It deals good damage and is extremly vital to reposition your soldiers.

Third Max: E
This skill is for escape, engage and damage. You can dash farther if you used your Q before to send your soldier to dash to farther. It gives a good shield which could decide the fight.

Last Max: W
Leveling his W literally does nothing. His sand soldiers damage and the damage on turrets both scale only with ap and Azirs level.

Ok for the runes I use mainly offensive ones for his early pressure in lane or late game scaling ones because of his good late game scaling. I tried a bunch of other rune combination but this is by far the best i think.

Azirs damage output solely relies on his sand soldiers. They are his main damage. Try to have as much as you can in a fight and reposition them as muc has you can otherwise you won't deal as max damage as you could with them. When the enemy tries to engage you or your teammates and you have no q ready currently ( even though his q has 3 seconds cd on 40% cdr) use your ultimate to knock the enemies back from you to your sand soldiers and hold them there.

Just a little information for everyone trying to learn Azir. Currently he is still very bugged. Especially the bug, which appears at random, where after he uses q his sand soldiers are not able to attack / deal damage until they expire or are repositioned with your q again. It is currently the reason I won't use him on rankeds too. Riot already knows about this bug and hopefully they fix it soon.