Doom curse

You curse a creature within range, whenever that creature would take an amount of necrotic damage, it takes that much +1 necrotic damage. This spell can stack. If more than one instance of this spell is placed on a target, the additional damage from each instance is added up Then combined with the original damage source, dealing one large instance of damage.

At higher levels, you may copy this spell once for each level above first, you may choose new targets for the copies.