Azir

They Have Overstepped

Lane harassment and consistent damage output.

Burst damage and target access

Electrocute

Hitting a champion with 3 separate attacks or abilities in 3s deals bonus adaptive damage.
Taste of Blood

Heal when you damage an enemy champion.
Ghost Poro

When your wards expire, they leave behind a Ghost Poro. The Ghost Poro grants vision until discovered. Gain permanent AD or AP, adaptive for each Ghost Poro and when your Ghost Poro spots an enemy champion, plus bonus upon completion.
Treasure Hunter

Unique takedowns grant additional gold the first time they are collected.

Empowered abilities and resource manipulation

Transcendence

Gain bonuses upon reaching the following levels:
Level 5: +5 Ability Haste
Level 8: +5 Ability Haste
Level 11: On Champion takedown, reduce the remaining cooldown of basic abilities by 20%.
Gathering Storm

Gain increasing amounts of AD or AP, adaptive over the course of the game.

Electrocute is a great damage keystone choice for Azir as you're able to easily proc for bonus lane poke damage with a [Q] and a few autos.

Taste of Blood's bonus healing plays a huge role in empowering your ability to lane aggressively and trade without having to recall constantly.

Ghost Poro's bonus stats and vision are great for snowballing leads where you are able to stay on the aggressive.

Ravenous Hunter further empowers your ability to trade aggressively in lane and sustain during late-game teamfights with your massive damage scaling.

Azir likes to opt for big AP items so the extra CDR from Transcendence goes a long way for keeping your [Q] off cooldown for mid-game fights.

Azir is all about that late-game scaling and Gathering Storm doubles down on your ability to carry in 30+ min games.