Iron Mage’s Ring of Wizardry

Ring, artifact (requires attunement by a sorcerer, warlock, or wizard)

You can use an action to speak the ring’s command word and gain one spell slot each of levels 1, 2, 3, and 4 (if you are a warlock, you instead gain two warlock spell slots). Once you use the ring, it can’t be used again until you finish a long rest.