Patronize

You perform an arcane ritual to grant a scintilla of your power to a willing creature. Upon completion of the ritual, the target gains a level of Warlock and becomes bound to your service. Once per short rest, you can cast Sending, targeting your warlock.

The powers you grant the target are permanent and not revocable by you directly. Your warlock will perform what you ask of it to the best of its ability, provided that you keep rewarding it with magical powers in the form of essences. Each essence that you provide to your warlock increases its level by one. After level 5, you need to provide rare essences. After level 10, you need to provide very rare essences, and after level 15 you must provide legendary essences. If you are unable to provide it with essences, your warlock might stop obeying your commands.