Blackout

When you cast the spell on a caster, make an ability check with your spellcasting ability equal to 10 + the target's spellcasting ability. On a success you can prevent the creature from casting any spells of 3rd level or lower, excluding cantrips, for the spell's duration. However, you are unable to use any spells of 3rd level or lower for the duration as well. The effect ends early if the black stone is destroyed.

At Higher Levels. When you cat this spell using a spell slot of 4th level or higher up to 6th level, you and the creature are unable to use spells equal to or less than the level of the spell slot you used.