Last updated a month ago for 10.5 Patch
6 Inferno became largely popularized in patch 9.24B, and has stuck around a solid option when you find many defensive items. 6 Inferno will do immense damage over team, so finding lots of defensive items will ensure your team stays alive long enough for the enemy to burn.
When you find a lot of defensive items, or are able to find early Inferno units such as Kindred or Zyra.
In the early game, Nasus or any warden really will be a huge help to hold your defensive items that will later go on Amumu. Try to get 3 inferno as soon as possible and start win streaking.
By the mid game you definitely want to have your Kindred + Varus combo up as this will help the most in win streaking through the mid game. Continue to use a warden front line and start putting in your best units while you slowly level up to 7 and 8.