The Nightmare Dungeons are the most important part of the endgame content in Diablo 4. After you have completed the construction of your Renown farm and have started concentrating on bringing your character up to level 100, which is the highest possible level, this is where you will spend the majority of your time in order to reach the maximum potential level. Nightmare Sigils, which can be crafted all the way up to Tier 100, are the only way to enter the scaling Nightmare Dungeons, and you will...