Main champions to focus on for now would be Diana, Vayne, Zyra, Varus, Malzahar. This sets you up with the Inferno buff and Ranger(2) buff to start out and preps for your summoner buff for Mid Game play. Since this is a build meant for Attack Speed I try my best to focus on building at least 2 Guinsoo's Rageblade.

For Mid Game work on finding Azir for your Summoner buff. Then aim for your Ranger(4) buff with Kindred and Ezreal. If you haven't gotten your hands on Malzahar and you have a Kindred already, fill with Sion and to add a buffer to the front line until you have him. You should also be selling off your Diana at this point and replacing it with one of the Inferno/Rangers or Inferno/Summoners if you can, or wait til you can unlock Annie if it means you'd lose your Inferno buff.

By now you should have a minimum of Inferno, Summoner and Ranger(2, preferably 4). If not you'll want to focus on completing that task or risk having a ton of losses. The only exception I've run into is if you managed to craft several Guinsoo's Rageblade and your Ranger's are managing to keep your team afloat despite not having the summoner pets as your "front line". I've actually had a game where I had several Attack Speed buffs on my team so I was ending rounds under 10seconds because my Rangers were so buffed.

Find Annie ASAP and have her replace Azir. Her summon of Tibbers is great at making other teams focus on it instead of your Rangers unless your Rangers scattered outwards or Kindred leaped into the enemy's backline. Find your final Rangers(6) Ashe and Twitch.

Main items for this build: Guinsoo's Rageblade, Hextech Gunblade, Statikk Shiv, Zeke's Herald.

Bonus items: Repeating Crossbow, Giant Slayer, Spear of Shojin, Rapid Firecannon, Zephyr, Sword Breaker, Hush, Ionic Spark, Luden's Tempest, Runaan's Hurricane, Red Buff .

Situational items: Warmog's Armor, Dragon's Claw, Thornmail, Guardian Angel, Inferno's Cinder, Frozen Heart, Hand of Justice, Frozen Mallet.

Force of Nature Champions: Lux (Crystal or Glacial > Inferno or Shadow), Skarner, Taric, Warwick, Braum, Volibear, Olaf. Helps add to the build giving you a stronger frontline to protect your Rangers if you choose any of the melee Champions.