Void Purge

You speak the tongue of the mysterious crusader which echos from a different realm of existence. Weaving the shadows gifted to you, they solidify as you utter his name. The shadows fly toward the target destination and open allowing the crusader's voice to be heard. The sound resonates in every language within a 30 ft sphere of your choosing. All creatures within the sphere that have available spell slots must make a Intellegence saving throw. On a failure, a creature loses their highest level available spell slot. On a success, a creature loses their lowest level available spell slot. The creature recovers the spell slot after a short or long rest.