Focus of the Pact Keeper

uncommon (+1), rare (+2), or very rare (+3) (requires attunement by a warlock)

While holding this focus, you gain a bonus to spell attack rolls and to the saving throw DCs of your warlock spells. The bonus is determined by the focus's rarity.

In addition, you can regain one warlock spell slot as an action while holding the focus. You can't use this property again until you finish a long rest.