Dark Familiar

You summon a quasit or an imp (your choice) and attempt to convince it to serve you as a familiar. The fiend appears in an unoccupied space within range and can act immediately in any way it chooses, including attacking you. If you can convince the fiend to become your familiar within one hour - whether through magical coercion, intimidation, or by appealing to its evil impulses - then it forms a telepathic bond with you. If you do not convince it to serve within this time, then it vanishes, returning to the plane of its origin.

While you are bonded, you can sense what your familiar senses as long as you are within 1 mile of each other. While the familiar is within 10 feet of you, you share its Magic Resistance trait. Your familiar acts independently of you, but it always obeys your commands. In combat, it rolls its own initiative and acts on its own turn. When the familiar drops to 0 hit points, it disappears, leaving behind no physical form. It reappears after you cast this spell again.

As an action, you can temporarily dismiss your familiar. It disappears into a pocket dimension where it awaits your summons. Alternatively, you can dismiss it forever, sending it permanently back to the plane of its origin. As an action while it is temporarily dismissed, you can cause it to reappear in any unoccupied space within 30 feet of you. Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.

You can't have more than one familiar at a time, whether it was summoned by this spell or another method. At any time and for any reason, the fiend can end its service as a familiar, ending the telepathic bond and returning to the plane of its origin.