Nightosphere amulet

The Nightosphere Necklace first appeared in Daddy's Little Monster. It has the ability to turn anyone who wears it into the most evil and powerful demon in the Nightosphere.

Trivia

 * This necklace has been worn by Hunson Abadeer, Finn and Marceline. Although Finn says he is "pure of heart" even this necklace turned him evil.
 * The most notable change the amulet has on its wearer is changing their alignment to Chaotic Evil. Hunson Abadeer seems completely unaffected by this effect(presumably due to him already being Chaotic Evil). Marceline becomes completely unstable, enacting punishments on the citizens of the Nightosphere at random. Finn briefly retains his heroic resolve, helping Marceline and Jake escape, but moments later he tries to return Marceline to the Nightosphere.