Truthtelling Cauldron

Wondrous item, rare

The mouth of this pewter cauldron may be fastidiously carved to resemble the open, leering mouth of a demon. When the cauldron is filled with a boiling liquid, it seethes with floating bubbles that resemble leering eyes. Creatures and objects p l a c e d inside the cauldron have immunity to fire damage if immersed up to the neck (a Medium creature must be willing or immobilized to be put in the cauldron, but smaller creatures can be placed within if willing or restrained), or resistance to fire if only part of their body is within. If a creature is wholly or partially inside the cauldron and it tells a lie, they lose this protection from fire damage for 1 minute, taking 1d6 fire damage per round if part of their body lies within or 10d6 fire damage if wholly inside. A creature damaged in this way can attempt to hide this fact by succeeding on a Charisma (Deception) ability check, made with disadvantage, opposed by the Wisdom (Insight) ability checks of onlookers.