First things first before using Fortress, or, any jungler for that matter, you should understand a jungler’s responsibility. Farm efficiently, and help your carries get fed. I’ll let the build do the talking for itself. With that being said, the atlas is optional but do consider it against opponents of the likes of Ringo, Baron, Adagio, etc. It helps maim others attack speed like Grumpjaw, Kensei, WP Blackfeather, WP Skye, Silvernail, and many more. The aegis is for blocking Celeste b ability or Lorelai’s a as well as Gwen and Ringo’s Ults.