The Idol of Zeroth (5e Equipment)
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Wondrous Item (idol), artifact (requires attunement)
A small Ivory Idol that depicts three tentacles wrapped around each other. This Idol contains the Soul of Zeroth, a dangerous and evil Wizard who was killed and his soul trapped in the Idol. The Idol was placed in a secret place to keep people from finding him and freeing and resurrecting him.
Zeroth is a chaotic evil wizard with Intelligence 18 (+4), Wisdom 16 (+3), Charisma 15 (+2). He is very sarcastic and likes to insult people of all creeds and types. He always has something to say at someone's expense, even if his host is the only person who hears him. He wants to be resurrected so that he can continue his terror on the land.
Curse. Upon a person touching the Idol, Zeroth's soul exits the Idol and enters the person/character. They now have the soul of an evil wizard in their body. If a character that cannot be possessed touches the Idol, nothing happens, and Zeroth's soul is still trapped in the Idol. He has no control over them and no direct influence over them. However, he can attempt to persuade them to perform certain actions. He will try to convince his new host to take him to his crypt and resurrect him. He promises a reward, but does not tell them what it is (Spoilers, he kills them). While the person has Zeroth's soul within them, they are immune to being charmed or frightened. When the soul first enters them, and upon being targeted by any spell, the host takes 2d10 psychic damage.
If Zeroth is revived, use the Mage or Archmage from the Monster Manual for Zeroth's Statblock, accounting for Party Level. Replace and add spells at your whim.