Soulkeeper Pendant

Wondrous item, rare (optional attunement)
  A tool of devilish origin, these mundane-looking miniature animal skulls are designed to increase the throughput of souls to the hells. When a humanoid dies within 5 f eet of the pendant and the pendant doesn’t already have a soul trapped in it, its soul becomes trapped in a flame-filled hell-like demiplane causing the pendant’s eyes to glow fiery red. Casting remove curse or similar magic on the skull releases a soul from its captivity.
  Souls are stored indefinitely; a creature holding such a pendant that contains a trapped soul can use a spell like revivify to restore the soul to its body even after the corpse has been dead for more than the spell’s specified time limit (e.g. 1 minute in the case of revivify). A creature who is resurrected after its soul has been stored within the pendant must make a Wisdom saving throw or develop one long term madness effect. The DC for the saving throw equals 10 plus the number of days the soul was trapped in the pendant.
  Optional Attunement: Sellsoul. Upon attuning to this pendant, a devil, Eebezelbub, appears to you with an offer. She will trick souls you capture into following her to hell in exchange for granting you minor favours. When you capture a soul you can, as an action, call Eebezelbub’s name and permit her entry to the pendant. Roll a d6. On a 1, the soul refuses Eeb’s offer and drifts away, causing the animal’s eyes to slowly dim. On a 2-6, the soul accepts her offer and the skull flashes brightly before petering out. Eebezelbub reappears 1d20 minutes later offering to perform one of the following tasks:
  • She can deliver and return one message as per the sending spell, though she can’t enter the positive planes or heavens to deliver a message.
  • She can answer three questions as per the commune spell.
  • She can divulge information on a topic as per the legend lore spell.