Tier 2 Epic enchantment

Casting Time: 1 action or 10 minutes
Range: 5 feet
Components: V, S, M (a whip made from humanoid leather)
Duration: Concentration, up to 8 hours or permanent

You completely subjugate a creature that you can see within range. It must succeed on a Wisdom saving throw or be charmed by you for the duration and cannot act unless you will it. While the creature is charmed by this spell, you have a telepathic link with it across any distance or planar boundary. You can use this telepathic link to issue commands to the creature while you are conscious (no action required) which it obeys to the best of its ability. At the end of each of its turns, a creature charmed by this spell can repeat the saving throw to temporarily end the charm effect. On each of your turns over the spell’s duration, if a creature affected by this spell is not charmed, you may use your action to force it to succeed on a Wisdom saving throw or become charmed by the spell.

This spell may be cast with a casting time of 10 minutes. When cast in this manner the spell’s duration becomes permanent. The target can attempt a single Wisdom saving throw at the end of each year to end the effect.

This spell immediately ends if you cast it again before its duration ends.

Ref: ELCR p94