1st-level enchantment
Casting Time: 1 bonus action
Range: 90 feet
Components: V, S, M (the petrified eye of a newt)
Duration: Concentration, up to 1 hour
You can place a curse on the creature which you able to see within a range. But until the spell ends, you can easily deal an extra 1d6 necrotic damage for the target whenever you hit on it with an attack. Whenever you cast this spell you also need to chose one ability. Of course, the target has the disadvantage on an ability checks which is made with the chosen ability.
You can easily use the bonus action on a subsequent turn of yours for curse a new creature but it happens if the target drops to 0 hit points before this spell will end.
This spell ends as early as possible when whenever a remove curse cast on the target.
At Higher Levels:
Whenever you cast this spell by using the spell slot of either 3rd level or 4th level and of course you can maintain your concentration on the spell for a sake up to 8 hours. Whenever you use the spell slot of the 5th level or more than 5th level then you can easily maintain your concentration on the spell for up to 24 hours.