Arcanaphage Stone

Wondrous item, rare (requires attunement)

This smooth rock serves a similar function as rocks found in a bird’s gizzard and helps the arcanaphage digest magic. While you hold or wear the stone, you have advantage on saving throws against spells.

Additionally, you can use a reaction to counter a spell cast within 30 feet of you as if you cast counterspell. Unlike the spell, you must always make a spellcasting ability check (using Charisma as your spellcasting ability if you do not have one), no matter the spell level. If you successfully counter the spell, the stone increases its Absorption score by 1. Its Absorption score cannot exceed 8. Once you have used the stone to counter a spell, it can’t be used in this way until the next dawn.

Finally, you can use an action to throw the stone up to 60 feet away to unleash its stored magic. When it reaches its target, it explodes, and each creature within 5 feet per Absorption score must make a DC 14 Dexterity saving throw, taking 1d6 force damage per Absorption score on a failed save, or half as much damage on a successful one. This destroys the stone.