Polaris Magistrate Robe (Patreon)

Wondrous item, rare (requires attunement by a lawful creature)

These robes are worn by the elected officials of Polaris, a floating city held aloft by astral magic. While wearing the robe, you can't be charmed, and you have advantage on Wisdom (Insight) checks made to determine if a creature is lying. In addition, you can choose to intensify your voice at will, causing it to boom up to three times as loud as normal each time you speak.

Truth, Unassailable.