Be careful about putting down both of the soldiers stored by Arise! Unless you're going all-in, always have a soldier in your back pocket if you need to escape over a wall or if you misposition your other soldier and need damage now.
In the lane, try to position your soldiers between the enemy's minions and the enemy champion. This way you can use them both to last hit and to project threat onto your lane opponent.
Think of Emperor's Divide as a defensive ability first and foremost. Use it when the enemy engages on you or your allies. Remember that your team can walk through the soldiers summoned by Emperor's Divide and use this to your advantage when enemy melee champions engage on you.
Azir'sConquering Sands will move his soldiers relative to where the soldiers were placed. The soldier placed first will move to the location of Azir's cursor at the time conquering sands was cast. The second soldier will move to the right of Azir's cursor, and the last soldier placed will move to the right of where Azir's cursor was. Their movements do not depend on how close they are to the target.
Nashor's Tooth is an ideal item for Azir, and in many cases will most likely be your first completed item. While expensive overall, Nashor's Tooth gives Azir Ability Power, Attack Speed, and CDR all in one item, granting an early spike in both burst and sustained damage that few other items can replicate. It is recommended that Fiendish Codex be your absolute first buy thanks to the early AP and CDR.
This is a somewhat controversial choice for Azir, as the on-hit damage from Nashor's Tooth is not triggered by his soldiers.
Despite Azir's sustained damage playstyle, his kits reliance on low-cooldown spells for damage and utility can cause Azir to run low on mana early on. How to mitigate this issue is up to the player, but options include:
Catalyst the Protector into Rod of Ages can give Azir both in-lane sustain due to its HP/Mana regen passive and steadily increase his HP (helpful for Shifting Sands's HP ratio), mana, and Ability Power as the game goes on, making it a valuable lategame item.
Morellonomicon grants CDR, a lot of AP, and decent mana regen on its own. The Grievous Wounds from its passive can also be extremely helpful. This is because Azir'sSand Soldiers apply spell effects while dealing damage in a line, meaning Grievous Wounds can be inflicted against multiple enemies quite effectively, making it quite helpful against enemies with heavy sustain.
A Tear of the Goddess would arguably be the most lategame-focused mana item to pick, offering solely mana and mana regen. However Azir's relatively low-cooldown kit means he can build up Mana Charges quite quickly. Once it's been upgraded to Archangel's Staff it will give a respectable boost to AP, and after transforming into Seraph's Embrace it will grant Azir a very helpful means of defense.
It is not recommended to build Sheen or any items that build out of it; Azir's soldiers apply spell effects only, and thus do not benefit from Spellblade in any way.
Liandry's Torment can be very helpful against a team full of tanks or bruisers; its HP% burn passive can be applied and quickly refreshed through Azir's Sand Soldiers, and Conquering Sands' slow will briefly double the % max health burnt. The AP and Magic Penetration benefit Azir's damage overall, while the HP will benefit the shield gained from Shifting Sands.
While it offers little offensively, Randuin's Omen can be a very powerful defensive item in a variety of situations. The Armor and Health improve general durability, while the HP specifically will grant a more powerful Shifting Sands shield. Although in an ideal situation Azir shouldn't be in range to make use of Cold Steel, the active can give Azir a last-ditch escape against enemies that get too close.
Azir thrives on dynamic positioning and quick repositioning. On top of its raw stats, Banshee's Veil's passive can assist in making Azir even more slippery and more difficult to lock down by blocking potentially lethal CC.
While most of his skills don't have very high AP ratios, the Sand Soldiers from Azir'sArise! have a very respectable one. Being the focus of his damage by replacing his autoattacks, Rabadon's Deathcap can give Azir absolutely devastating damage.
Zhonya's Hourglass is a very useful item for Azir, granting a large amount of AP, respectable Armor, and an active that can negate potentially massive amounts of damage. If you have a secure lead and are doing well, you can potentially get away with this as your lone Armor-based item.
Rylai's Crystal Scepter is incredibly effective on Azir. The slow is applied on all of his abilities and his soldier's attacks, both providing additional CC, and making it more difficult for opponents to escape his soldiers. The health increase is also a nice addition to his defenses and the shield scaling on Shifting Sands.
Azir's Sand Soldiers are untargetable and can only be moved via Conquering Sands; with proper positioning and timing, you can bypass the soldiers and strike Azir directly.
Aside from Emperor's Divide, Azir has relatively low cooldowns. As such it would be best to engage on Azir based on his available mana rather than his spells, which are almost always going to be available before a fight.
Azir's secondary role is that of Marksman for a reason: his damage is most often dealt over a sustained period of time and based primarily on his autoattacks. Making him a high priority for burst and CC or somehow reducing his attack speed will significantly mitigate his threat level.
Azir can be built as a bursty glass cannon, sustained DPS Ability Power Carry, or tanky AP bruiser. Determine the build path being taken based on Azir's items, then adjust your approach accordingly.
Shifting Sands is his only escape, which even at max CDR has a cooldown of below 10 seconds. If you can bait Azir into using it offensively or otherwise preemptively, then he can be quickly locked down and eliminated.
Azir reaches his full potential in the late game, where his heavy sustained damage and utility can sway teamfights drastically. The tradeoff for Azir's strong late game power is his weak early game. By picking to counter him and/or co-operating with your Jungler, you can help shut him down early game.
Emperor's Divide provides great utility in teamfights and blocks most dashes. However, it does not block blinks, so champions like Warwick, Zed and Kassadin can bypass the wall and assassinate their targets. Champions like Vi, Malphite and Hecarim can also bypass the wall with their ultimates.