Amulet of the Night Sky

The Amulet of the Night Sky is a slice of lapis lazuli roughly four inches across set into a gold disk and hanging from a spiraling chain. The back of the disk is a map of the stars, though they don't quite line up with the visible constellations that you can see. By looking deeply into the stone, patterns begin to emerge in the golden flecks within, showing constellations alien and strange to your eyes.

The Amulet of the Nigh Sky holds one charge, which recharges at sundown.
To use, roll a d12. The corresponding constellation appears in the disk until it recharges and you gain the corresponding effect:

1 -- The Thief.  For the next 8 hours or until the sun rises, you are considered proficient in stealth and with thieves tools. You may cast pass without trace once, ignoring the material component cost. Doing so ends other effects caused by this item.

2 -- The Arcanist.  For the next 8 hours or until the sun rises, your AC increases by 5 against magical attacks and damage (think of this a prolonged Shield spell) and you have advantage on saving throws against magical effects.

3 -- The Warrior.  For the next 8 hours or until the sun rises your AC increases by 5 against bludgeoning, piercing, and slashing damage. You also gain proficiency in martial weapons and heavy armor until this effect ends.

4 -- The Ritual.  For the next 8 hours or until the sun rises, the sound of eerie unintelligible chanting fills your ears, and the faint smell of incense lingers around you. You may cast animate dead (3rd level) ignoring the material component cost. Doing so ends all other effects caused by this item.

5 -- The Elemental.  For the next 8 hours or until the sun rises your AC increases by 5 against fire, cold, and electrical damage. You may charge your attacks with fire, cold, or electrical damage for one hour adding 1d6 of the respective elemental damage to attacks you make for one hour. Charging your attacks in this way ends other effects caused by this item.

6 -- The Shadow.  For the next 8 hours or until the sun rises, your movements make no sound and you cannot be heard above a whisper when you speak. You may cast the spell Darkness at a second level once while this effect is active, ignoring the material component cost. Doing so ends other effects caused by this item.

7 -- The Stallion.  For the next 8 hours or until the sun rises, you gain +5 to your movement speed and can speak to horses. You may cast haste once  while this effect is active at a second level ignoring the material component cost. Doing so returns your movement speed to normal and ends all other effects caused by this item.

8 -- The Lady. For the next 8 hours or until the sun rises, you are physically transformed to look like the last humanoid female you saw that you considered "beautiful," as if under the effects of the alter self spell, however this form is fixed until the duration of the effect. You may cast the spells Sleep (at 3rd level) and charm person (at 3rd level) once each while this effect remains. Doing so ends all effects caused by this item.

9 -- The Tower.  For the next 8 hours or until the sun rises, you gain advantage on checks you make pertaining to architecture. You may cast either Knock (at 2nd level) or Meld into Stone (3rd level) once while this effect is active. Doing so ends all effects caused by this item.

10 -- The Lovers.  For the next 8 hours or until the sun rises, you gain temporary hit points equal to half of your maximum hit point total. You also take notice of a spectral from visible only to you that has the appearance of your current or most recent significant other, which only you can see. This specter is invisible, intangible, completely silent, and always remains just out of reach of your touch. This specter vanishes when the effect ends or when the temporary hit points granted by this effect are expended.

11 -- The Serpent.  For the next 8 hours or until the sun rises, you gain immunity to poison and may speak to snakes and serpents. You may cast the spell Acid Arrow (3rd level) once before this effect ends. Doing so ends other effects caused by this item.

12 -- The Lord.  For the next 8 hours or until the sun rises, you are physically transformed to look like the last humanoid male you saw that was in a position of authority over you, as if under the effects of the alter self spell, however this form is fixed until the duration of the effect. You may cast the spell Command (at 1st level) three times while this effect is active. Doing so three times ends other effects caused by this item.