Blood Link

You touch a creature, and that creature must succeed on a Constitution saving throw or become cursed for the duration of the spell.

Each time you take damage that isn't psychic damage, the target takes necrotic damage equal to the damage dealt to you.

A remove curse spell ends this effect. If this spell ends due to you losing concentration as a result of taking damage, the target doesn't take the damage they normally would have from being cursed while you took that damage.