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From Pathfinder Lost Omens Rival Academies, which isn't enabled.

Oathlamp of Accord

ITEM 3
Price 50 gp
Usage held in 1 hand
Bulk L

This hooded lantern takes the form of a translucent prism. It functions as a normal Hooded Lantern, except that it isn't fueled by oil, but by oaths. While you're holding the lantern, you gain a +1 item bonus to Diplomacy checks.

Activate—Announce Oath (light, mental)
Trigger You make a promise in good faith

Effect The oathlamp of accord sheds light without consuming fuel until the promise you made is broken or fulfilled. The GM adjudicates whether a spoken promise is broken or fulfilled. This light and the shutters to conceal it work as normal for a hooded lantern. Any creature in the light of the oathlamp becomes aware of the contents of the oath, along with who made it and how long ago.
Pathfinder Lost Omens Rival AcademiesORC