Nightosphere amulet

The Nightosphere Amulet first appeared in the episode, "It Came from the Nightosphere" as part of Hunson Abadeer's clothing. During "Return to the Nightosphere," it was revealed to be a removable amulet that Hunson was wearing that gave him his powers. It has the ability to turn anyone who wears it into the most evil and powerful demon in the Nightosphere.

Appearance
The amulet is a pink rhombus shaped gem. It is connected to a gold chain that part of the gem. When worn, the amulet grants the wearer a business suit. The amulet itself becomes part of the suit as the top part of a tie.

Abilities
The amulet grants the wearer the ability to transform into the most evil creature in the Nightosphere. Upon wearing the amulet, the wearer will become dressed in a black business suit. Wearers of the amulet gain the ability to suck the souls of the living, as well as transforming in to a very powerful demon and ruler of the Nightosphere. The wearer will lose all powers and their demonic form if the amulet is removed.

Trivia

 * This necklace has been worn by Hunson Abadeer, Finn, and Marceline. Although Finn says he is "pure of heart", this necklace turned even him evil (and possibly gave him trauma).
 * The appearance of the demon seems to change from wearer to wearer. Marceline and Hunson's demonic forms were mostly the same, with little more than differing colour schemes to tell them apart, while the demonic Finn had a large white head with bulging, colorless eyes.
 * The most notable change the amulet has on its wearer is changing their alignment to Chaotic Evil. Hunson Abadeer seems completely unaffected by this (presumably due to him already being Chaotic Evil; however, he does acts nicer without it on in "Return to the Nightosphere"). 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.
 * The amulet may also harbor restoration magic, as it can easily be pulled away from the person's neck from the back, and not be damaged or cut.
 * The amulet comes with a suit for the wearer.
 * The amulet resembles the Holo-Pendant that Princess Bubblegum gave Finn in "The Other Tarts."
 * When Finn and Hunson Abadeer took off the amulet, the evil and chaos went back into the amulet. When Finn and Jake took it off of Marceline, the evil fell off and soaked the demons.