Create Spellstone

You conjure raw magic and infuse the gemstone used as the material component for this spell with it, which increases the potency of all spells you cast while it is in your possession. While you hold the spellstone, your spell damage dice "explode." (When you roll damage for a spell and roll the highest number possible on any of the dice, roll it again and add that roll to the damage.)

The spellstone is unstable. Whenever your spellstone triggers, roll a d20. If you roll equal to or less than the number of dice that exploded, the spellstone explodes. You and creatures in a 20-foot radius from the stone must make a Dexterity saving throw against your spell save DC. Creautres take 1d10 force damage times the spell's level (minimum of 1d10) on a failed save, or half as much damage on a successul one.

The gemstone only functions for you--it becomes inert when in the possession of someone else. The stone crumbles to dust after the duration, or when you destroy it during your turn (no action required).

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the duration is 8 hours. If you use a spell slot of 7th level or higher, the duration is 24 hours. If you use a 9th level spell slot, the spell lasts until it is dispelled.