The Nightmare Amulet is a craftable item found in the Magic Tab. It costs 6 Gold Nuggets, 4 Nightmare Fuel, and 2 Purple Gems to craft and requires a Shadow Manipulator to prototype. It can also be dropped by an Ancient Pseudoscience Station when it is damaged with a Hammer, Gunpowder, etc. It can be equipped in the chest slot and lasts for 3 minutes and 12 seconds (2/5th of an in-game day).
While it's equipped, the Nightmare Amulet allows the player to experience the effects of 0 Sanity without actually setting the character's Sanity to 0. The screen will become distorted with the usual low Sanity effects, and Shadow Creatures will spawn. While under effects of the Nightmare Amulet, more Shadow Creatures will spawn and more frequently, compared to the player being insane without the amulet. During this time, the player's Sanity will start dropping by 3.33 per minute.
- This item can be useful for collecting items that are only available at low Sanity levels, such as Beard Hair and Nightmare Fuel, while still being able to opt out of the dangers of insanity at will.
- This item can be especially useful when playing as Maxwell, since not only does his Sanity regeneration make it hard to go insane the normal way, but it also mitigates the Sanity loss caused by the Amulet.
- Using the Nightmare Amulet to its full potential to farm Nightmare Fuel can yield around 20-24 Nightmare Fuel.
- The Nightmare Amulet will almost always spawn a Shadow Creature upon equipping it. Paired with a low Sanity level, this can be utilized to spawn Shadow Creatures, and unequipping the amulet will not despawn them. This can be used to obtain more Nightmare Fuel.
- The Nightmare amulet can be used to lower your lunacy on the lunar island.
- The Nightmare Amulet shares the same in-game model with Magiluminescence, but its gem is purple instead of yellow.
- Prior to the The Stuff Of Nightmares update, the Nightmare Amulet actually restored 2 Sanity per minute, instead of reducing it.
- This item was previously crafted from the Gemology Tab before the latter was removed from the game.
- The gem in the Nightmare Amulet has eight corners, however the Purple Gems used to craft it only have six.
- According to Wickerbottom and Maxwell, the Nightmare Amulet communicates with the shadows.
- Eating a Grim Galette while wearing a Nightmare Amulet will instantly kill the player due to its effects.