You gain the ability to sub-divide your pact magic. As an
action, you expend one of your warlock spell slots from
your Pact Magic feature, and you gain a number of smaller
temporary spell slots. The level and number of temporary
spell slots gained depends on the level of the slot you
sacrificed, as shown in the Protean Magic Slots table. You
regain the sacrificed spell slot and lose the temporary spell
slots when you next finish a short or long rest.
Once you use this feature, you must finish a short or long
rest before you use it again.