I wanted to lean harder into the infernal nature of devils (contracts, fire, etc) and make them prominent for this theme. This circlet relies a lot on the GM to adjudicate, but I like the idea of forcibly entering others into a devilish contract without their knowledge. It's something an evil devil might do.
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A fiend lord typically grants such circlets to worshipers who expounds the ideals of trickery and the deceptive scam of "fair trade." It is never quite clear who benefits from this trade: the wearer or the fiend who owns the circlet.
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Circlet of the Contract
Wondrous item, rare (requires attunement)
While you wear this circlet, you have advantage on Charisma (Persuasion) checks.
Devil's Contract. This circlet has 3 charges and regains 1d3 charges daily at dawn. While wearing this circlet, you can expend 1 charge to cast suggestion from it. If you had recently fulfilled one of the target's desires within the past hour, the target has disadvantage on its saving throw.