Many of the best builds in Diablo 4 make use of powerful Aspects, which can be found on legendary weapon drops or by completing dungeons to acquire Aspects that are then added to your codex of power. You then take these Aspects to the Occultist to upgrade your gear. This guide covers how to acquire Aspects, how to look for Aspects that will suit your build, as well as when to upgrade your gear - as upgrading is an expensive business.