Because Emperor , no , really azir is a strong champion with a pretty strong laning phase and a very good mid-late game . Azir can beat imboile champions and/or short range champions such a Yasuo or Brand . the biggest problem of azir is that he is very weak against Blink's an/or long ranged gap-closers like Zed or Very long ranged champions such as xerath . but you can beat them if you play smart and you farm early , the good thing about azir is that he can play pasive he can W Q and farm with the soldiers . The Secret of playing with azir is MAX Q first (because W has already a good AP scaling and the base ap is pretty weak ) .
And Max W 2nd or last if you like to go all-in

-Pros - Good laning phase - "Safe" pokes - Escape Ability - Strong disengage With his ult - A F@#KING TURRET in his pasive - CC - Hes an Emperor

-Cons
- Squishy
- Mana hungry
- Long CD on his E
- Needs good positioning
- Pretty much a big mana cost or Pokes 110 mana
- No burst

Well combos are a lot pretty tricky because you must position your soldiers very well if you want to succed in killing and/or making your enemy know that this is your "playground"

This is a Haras combo

Summon a sand soldier near the enemy so and Then use Q to Deal dmg and then use another soldier AA to end the combo , its a pretty expensive combo , it can cost you 110 mana so dont try to use it to many times until you made your chalice

Escape-Turn around combo

Well this is combo looks pretty much like the first unless you use your soldier to escape

First use your W and E to Get back and then summon another soldier W and then Q on the enemy

Escape combo

This combo requires all your abilites (exept the ult ) . so use it wisely . Use W and the Q to the location where you need to go and then E , pretty easy right ? But you have to do this as fast as you can and dont use E to early or youll be hitting the wall or youll go just 3 units :P

All in combo

This (again ) requires your whole combo , BE sure you Have enough dmg , you must be calculated . use W x2 near your enemy and then AA , use Q to pass beyond your enemy , then use E to knock him up and deal dmg , and the Use R to Deals some dmg and Knock him up a little , if he doesnt die and he tries to run , dont worry just go TROUGH the wall to get the movement speed buff and use Q again to finish him OFF , ofc youl use ignite in this process

Your job as azir in Teamfights is to stay in a safe zone and let the soldiers do the job , dont rush your E in teamfights its your only escape (exept flash ) , and do not think to use your ulty as a damage tool , Azir's ult its better in TF if you use it in a utility mode .
FoR example their assassins want to reach you and your ADC and you can just ult , and their assassin must go around the wall or use flash to reach you , or as a disengage tool , its a really good ultimate but you must use it very carefully if you want to survive

Farming with air requires some practice tho . you Really need to learn how to use soldiers to farm well and positioning them is vital for you ( Especialy early game) . so thats why is
very likely to buy chalice of harmony , and remember , USE ONLY 1 soldier for farming because 2 of them dont deal so much dmg togheter and its better to keep 1 soldiers do escape in case of a enemy gank

As Azir , it is vital to roam , your CC can be compared to maokai's , your long range on Q and E are huge gap-closers so if you roam ( and your jungler comes to gank 2 ) its a guaranteed kill , Well ofc if they dont have janna , she can rly F$%K up your whole combo
If you have a Jungler with a LOT of CC such as Maokai or JarvanIV you can make easy kills , because their CC + your CC + your Dmg ( not that much early ) can make an easy kill , and you have carry junglers such as kha zix dont be angry if he takes the kill , the most important thing to do for you is farming think about it .17 = 300 g ( more or Less )

Azir build IS a Focused more on CDR , atack speed ( if you like ) AP , and being tanky
so Items that are NECESARY to build are :

Chalice/Athenes unholy grail :CDR mana regen , magic resist and that cool pasive that gives you mana back . SO : mana regen Checked , Tanky (MR) checked , AP Checked , CDR Checked

Rylay Crystal scepter : a very good item since its change for ap champs , 100 AP its a good amount of DMG and 400 HP are very good for azir + THAT COOL PASIVE WICH APLIES ON SOLDIERS BASIC ATACKS

Abysal Scepter : i dont recomend this item early game just if you lose your lane against ap mid such as fizz : for the next reasons : gives you ap , MR , and some penetration ( aura )

seekers guard a very good item and a must-buy when you are against ad mid . gives you , ap, amor and that paisve , and you need it early since Zhonyas is to expensive to finish early- mid game

Rod Of Ages : ROA on short is still a very good item : sustain , HP , AP , MANA , and that very good pasive , if you want to buy it , buy it over rylay

Nashors thoot : a very good item : CDR , Atack speed , And AP , why i dont incorporated in my builds is because i've diceded its kind of a waste because : you already have 40% cdr with the boots15% + runes masteries 10% + unholy grail 20% = 45% and 40% is the maximum
if you want to build nashors thoot : dont take CDR boots take magic pen boots instead , replace your points from sorcery to Fury and youre good to go , i suggest nashors thoot against yasuo for good outtrades

Rabadons deathcap : its a main item for ap champs , doesnt need to explain why i take this

WHAT NOT TO BUILD
: WARMOG ,RANDUINS OMEN , SPIRIT VISAGE , FROZEN HEART , Zephyr , BERSEKERS GREAVES , ETC

Flash : I pick This summoner Spell because azirs E cooldown is very big early and its better to have 2 escape abilites
Ignite : i take this because i can secure kills very easy with this summoner spell