Detaining Strike

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects, except the damage is halved. A beam of light surrounds the target, and slows it down. Until the end of your next turn, every 5 feet of movement the target takes costs it 10 feet.

This spell becomes more powerful when you reach certain levels. At 5th level, the target's speeds are reduced to 0. At 11th level, the damage of the attack is not halved. At 17th level, the attack deals an additional 1d8 radiant damage.