Critical Stockpile

Creates a stockpile of d8 dice, gaining one each time you crit.
When you cast a spell with a save, you also gain dice to stockpile, one for each enemy who rolls a Nat one on their save.

Critical stockpile d8s can be spent on any damage role (spells and attacks) but are not affected by criticals and don't double.
 Any number of dice can be used at once up to your proficiency modifier.

The max number of dice stored at once caps at 20.