You learn one additional invocation from the list available to you, choosing an invocation of one grade lower than the highest grade of invocation you know. For example, a 6thlevel warlock could learn a least invocation, while a 16th-level warlock could learn any least, lesser, or greater invocation.
You can gain this feat multiple times. Each time, you gain an extra invocation of any grade (least, lesser, or greater) up to one lower than the highest grade of invocation you can currently use.
