Anulus Custodi

The Anulus Custodi is also known as the Ring of the Protector.

Description
A brass ring with a small blue sapphire, engraved with Old Elvish runes.

Lore
The Anulus Custodi was created by the Elvish Emperor's artisans for the office of the High Priest, who oversaw religious ceremony throughout the Empire. When the Empire fell, the Anulus fell into the hands of the Ringlord Darvis the Cruel, who severed it from the last High Priest's finger.

Qualities
While wearing this ring, you are immune to magic that allows other creatures to read your thoughts, determine your location, determine whether you are lying, know your alignment, or know your creature type. Creatures can telepathically communicate with you only if you allow it.

While wearing this ring, you have advantage on saving throws against any spell that targets only you (not in an area of effect). In addition, if you roll a 15 or above for the save and the spell is 7th level or lower, the spell has no effect on you and instead targets the caster, using the slot level, spell save DC, attack bonus, and spellcasting ability of the caster.

You can use an action to cause the ring to become invisible until you use another action to make it visible, until you remove the ring, or until you die.