Source: Arcana Unleashed
Epic Boon Feat (Prerequisite: Level 19+, Spellcasting or Pact Magic Feature)
You gain the following benefits.
Ability Score Increase. Increase your Intelligence, Wisdom, or Charisma score by 1, to a maximum of 30.
Mastered School. Choose one of the eight schools of magic: Abjuration, Conjuration, Divination, Enchantment, Evocation, Illusion, Necromancy, or Transmutation. Your choice grants you the following features:
Rote Casting. Choose a level 1 spell from the chosen school that appears on your class’s spell list. You always have that spell prepared and can cast it without a spell slot or spell components.
Signature Arcanum. Choose a level 7 or lower spell from the chosen school. You always have that spell prepared. You can cast it once without a spell slot, and you regain the ability to cast it in this way when you finish a Long Rest.
You can also cast these prepared spells using any spell slots you have of the appropriate level.
Repeatable. You can take this feat more than once, but you must choose a different school of magic each time.