Nightmare Fuel

''"The harvest moon glows eerily." ''

Nightmare Fuel is a post-Moon Lord crafting material dropped by most Pumpkin Moon enemies after The Devourer of Gods has been defeated. It is occasionally used as an alternative to Endothermic Energy, or in conjunction with Endothermic Energy and Phantoplasm to make Ascendant Spirit Essences.

Trivia

 * "Nightmare fuel" is an informal term used to refer to highly disturbing content.
 * The tooltip may be a reference to the item of the same name from the game Don't Starve, which is obtained from insanity based creatures.