You attempt to enslave a creature that you can see within range. It must succeed on a DC 20 Wisdom saving throw or be charmed by you forever. If you or creatures that are friendly to you are fighting it, it has advantage on the saving throw.

While the creature is charmed, you have a telepathic link with it as long as the two of you are on the same plane of existence. You can use this telepathic link to issue commands to the creature while you are conscious (no action required), which it obeys as said to the best of it's ability.  If the creature completes the order and doesn't receive further direction from you, it defends and preserves itself to the best of its ability. Unless given specific orders , the creature will remain paralyzed . The creature cannot resist any commands. On disobeying , the creature will become frightened and the creature will see an imaginary illusion of their worst fear , which renders them paralyzed.

You can use your action to "free" the creature by casting the spell again on any monster enslaved by you ( assuming you have necessary components and spell slots).

The Thralldom only breaks if you willingly enter an outer plane or if you die. Note that casting the spell on a creature enthralled by someone else results in the caster being notified of the attempt , which ha no effect.

Only a wish spell or divine intervention via a cleric can dispel this effect