you have a curse one of those listed below or one deemed suitable by the DM.but in exchange for this you were gifted the ability to cast spells.you have one spell slot and can cast any warlock spell with it no preparation required.here are two sample curses:
speed loss. all your speeds are decreased by 10 ft.
weak. you have a -2 to strength score.

your unarmed strikes deal 1d4 necrotic damage instead of normal damage.

you may cast the find familiar spell once per long rest with one of the following as familiar options but you may cast any spell through your familiar.here are some additional familiar forms:,twig blight,Giant Bat,Giant Poisonous Snake ,Grung, or a skeleton.

you increase your dexterity score by 1 and your charisma score by 2.