"Let's make a deal..." 

 An iron armband, it appears ashen with smoke curling slowly around it, and is warm to the touch.

A creature wearing this band gains fire resistance and no longer requires food or drink. In addition, they gain curling horns of fire atop their head that produce 5 feet of bright light with an additional 5 feet of dim light. These horns cannot be turned off or be hidden and only disappear upon removal of the band.

Along with the above, the next time the creature takes a long rest after attuning to the band, a shadowy demonic figure appears in their dream and says the following with a smile, "I am the dealer, and you've entered a contract with me. From me you will receive power, and all I ask of you are favors in exchange. Now then, how about let's make a deal." The creature then awakens gaining the benefits of a short rest.

After this first encounter the Dealer will appear in the creature's dreams to ask favors. The creature may only make one deal with the Dealer per day, and the Dealer will only ask one favor per night if the attuned creature made a deal, this favor must always be an equivalent exchange. Equivalent is defined by your DM. The favors are always evil no matter the nature of the request. And the attuned creature feels a strong obligation to complete the favor within the next 24 hours. Some example trades are as follows and all are subject to the whim of the DM be that limits or trickery.

Deal of Form: The creature may ask the dealer to take the form of another creature, in exchange the dealer might ask them to begin skinning the creature while it lives and wearing it's skin/pelt.

Deal of Blood: The creature may ask the dealer to cure its ailments or restore health, in exchange the dealer might ask them to take a life to gain life.

Deal of Servitude: The creature may ask the dealer to make a beast a familiar, in exchange the dealer might ask them to kill the familiar of another.

Deal of Flight: The creature may ask the dealer for the power of flight gaining a flying speed double their walking speed, in exchange the dealer may ask them to rip the wings they wish to have off of the creature. For example, ripping butterfly wings off a butterfly.

Deal of Necromancy: The creature may ask for a servant or warrior to aid it on it's quest. The dealer might respond by pulling a soul from it's collection and binding it to the creature as a ghoul in exchange for another creature's soul. 

The creature has 24 hours to complete their end of the deal, but the effects happen instantaneously. If a creature does not complete their end of the bargain they must make a charisma save with DC 17. On a success, the dealer will ask for greater actions of evil as favors. On a failure, in that moment of weakness, the Dealer will take over the creature's body causing their alignment to change to chaotic evil. In addition they gain one level of madness with the following belief, "I am an aspect of the god known as cruelty." and the following flaw, "I love to make bargains, no matter what it may be.". In addition their appearance begins to become shadowy and demonic. The band loses all it's magical properties as a new one is created somewhere on the material plane after this happens.

If the creature dies while attuned to this band that creature's soul becomes added to the dealer's collection.

Notes: Resistance: Fire, creature that understands Infernal or Abyssal, Warding, Jewelry