Bloodcurdle

When you deal damage with any weapon treated with eldritch blood, you may use your bonus action to curse the target. The target must make a constitution saving throw against your spell DC. On a failed save the target takes 1d6 poison, 1d6 acid and 1d6 necrotic damage, and has disadvantage on their next attack roll, skill check or saving throw. On a successful save the target takes half damage