Umbral Curse

You place a magical command, compulsion, or curse on a creature that you are in contact with or poses a sufficient piece of (Such as a lock of hair, several drops of blood or deeply treasured personal item) The spell takes as much time to cast as it takes you to describe the parameters of the effect, speaking them aloud as the verbal components of the spell. This verbal component cannot be eschewed by metamagic. 

When you cast this spell on a creature it may make a Transference OR Charisma saving throw or suffer the conditions you describe during the casting of the spell for the duration. While the creature is under your curse, it takes 2d10 psychic damage each time it acts in a manner directly counter to your instructions. A creature that can’t understand you is unaffected by the spell.

When you cast this spell, choose the nature of the curse from the following options:

Command: The creature carries out a task you give it until it is complete. when dictating the curse to them there must be a determinable end to the task or the spell will fail. As such "Serve me forever" would cause the spell to fail however "Slay Aslack and return his head to me" would succeed.

Curse: given enough spell power this spell can create certain magical effects or conditions on top of the 2d10 psychic damage. these conditions and their repercussions must be made clear to the target as the spell is cast, or the spell will fail. As above the conditions cannot be vague, so again "Obey me" would not work. however if you were to say "So long as your debt to me is unpaid, you will obey me as my servant, and if you so much as think of moving against me you will be stricken with debilitating pain" would work (Though may require a higher level casting)

So long as parameters are clearly set and with DM allowance this spell can have other uses, these uses may require either divinity, special components, or some other prerequisite to function. 

Once the parameters above are met the spell ends with no ill effect to the target OR you can end the spell early by using an action to dismiss it. A remove curse, greater restoration, or wish spell also ends it unless cast at a greater level. (See below) other special effects can end the spell early, such as standing in the presence of a god, contact with a pure being (Like a unicorn) or undergoing rituals with components more potent then those used. All per DM discretion.

At Higher Level:

The duration, effects and potency of this spell are limited by the spell level used to cast it. The duration and dispel requirements of the spell is listed below and the effect is judged by the DM at the time of casting. if a target willingly fails their save then the spell will succeed even if the effect is above the intended level (Though it will still use the casters highest available level.)

4th: 1 week remove curse must be cast by a caster of equal or greater level then you when you cast it. if a lower level caster attempts to they must pass a transference save (DC 10+level difference) or suffer 5d10 psychic
5th: 1 month And lower level casters using remove curse have disadvantage
6th: 6 months Can only be removed by a greater restoration or wish
7th: 1 year Greater restoration cast by a lower level caster must make a transference save
8th: 1 year Can only be removed by a pure being or a wish spell
9th: indefinite Can only be removed by a fully ascendant god or by the wish spell