Source: Arcana Unleashed
Level 7 Enchantment (Bard, Sorcerer, Warlock, Wizard)
Casting Time: Action
Range: 60 feet
Components: V
Duration: 1 minute
You speak a word of power that causes waves of intense pain to assail one creature you can see within range. If the target has 100 Hit Points or fewer, it takes 6d8 Force damage and has the Charmed condition for the duration. Otherwise, it takes 6d8 Force damage only.
While the target is Charmed, its Speed can be no more than 10 feet, and it has Disadvantage on D20 Tests except Constitution saving throws. In addition, when the target tries to cast a spell, it must first succeed on a Constitution saving throw, or the spell dissipates with no effect, and the action, Bonus Action, or Reaction used to cast it is wasted. If that spell was cast with a spell slot, the slot isn’t expended.
At the end of each of its turns, the Charmed target makes a Constitution saving throw, ending the spell on itself on a successful save.