Mystic Arcanum

Your patron bestows upon you magical secrets called an Arcanum. Choose one spell from the warlock spell list, that is of the highest level you can cast, at levels 1, 3, 5, 7, & 9.

You can cast your Arcanum spells, at their chosen spell level, once without expending a spell slot. You may also cast these Arcanum using your Pact Magic feature. You must finish a long rest before you can do so again.

You regain all uses of your Mystic Arcanum when you finish a long rest.