Spell Theft (Bard, Sorcerer, Warlock)

Whether willingly or unwillingly, a magic user has given you knowledge of how to cast a spell that you perhaps would otherwise be unable to cast.

• Choose a spell from the bard, sorcerer, or warlock spell lists of a level less than or equal to that of your highest-level spell slot, and add that spell to your spell list. Charisma is your spellcasting ability for that spell. You may cast this spell once per long rest.
• The Spell Theft feat may only be taken once.