Boon of Spell Recall

Source: D&D 5.2 SRD Player Characters

Epic Boon Feat (Prerequisite: Level 19+, Spellcasting Feature)

You gain the following benefits.

Ability Score Increase. Increase your Intelligence, Wisdom, or Charisma score by 1, to a maximum of 30.

Free Casting. Whenever you cast a spell with a level 1-4 spell slot, roll 1d4. If the number you roll is the same as the slot's level, the slot isn't expended.