Charon’s Obol
Wondrous item, rarity varies
The rarity of this coin is determined by the metal it is made of. A common obol is copper, uncommon is silver, rare is gold, and very rare is platinum. While the coin is in the mouth of a dead creature, it bestows powers upon the corpse, detailed below. Each ascending rarity also grants the properties of the lesser rarities.
Copper. The corpse can’t become undead.
Silver. The corpse can’t be targeted by any necromantic magic.
Gold. The corpse is resistant to all damage and protected from decay. A creature that attempts to remove the coin from the corpse’s mouth must make a DC 15 Constitution saving throw or take 5d10 radiant damage and fail to remove the coin.
Platinum. The corpse is immune to all damage and can't be targeted by any divination magic or perceived through magical scrying sensors. A creature that attempts to remove the coin from the corpse’s mouth must make a DC 16 Constitution saving throw. On a failed save, the creature takes 10d10 radiant damage, fails to remove the coin, and is thrown 20 feet from the corpse. On a successful save, the creature takes half as much damage, removes the coin, and is not thrown.
In lands where necromancers roam and the dead are restless, it is a common burial rite to place an obol in the mouth of the deceased.