This ring, adorned with the symbol of Rakdos, allows you to cast hellish rebuke. A guild signet is sometimes awarded to a guild member whose renown score in that guild is 5 or higher, as a reward for performing special services for the guild. Aside from its magical properties, the ring is also an indicator of Rakdos' recognition and favor.
A signet has 3 charges, and it regains 1d3 expended charges daily at dawn. While wearing it, you can expend 1 charge to cast the associated spell (save DC 13).