A golden ring inset with  a black gem once worn by the captain of the guard of a long lost golden city. 

When equipped, the bearer may expand a charge to trigger the Boon of the Nightwatch. 

Boon of the Nightwatch is a instantaneous Enchantment spell with a duration of 2 rounds. 

• You gain Darkvision.  This effect persists for 12 hours after the duration of the spell, and is non-stackable. 
• You gain advantage on dexterity checks and saves.   This effect persists for 12 hours after the duration of the spell, and is non-stackable.  This effect is not negated by the effects of any other spell or condition. 
• When triggered, you are moved to the highest possible spot in the initiative order, effective on your next turn. This lasts for 2 turns, after which you resume your original initiative spot.
•  For two turns, your actions and bonus actions are doubled. 

When the spell ends, the ring bearer takes on 1 level of exhaustion.    

The Ring of the Nightwatch holds 6 charges.  At the end of a long rest, it regains 1D6 charges. 

Notes: a 48-hour unbroken vigil while wearing the ring. Cannot be attuned by anyone incapable of sleeping.