Urza's Rebuff

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 6rd level or lower, its spell fails and has no effect. If it is casting a spell of 7th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a success, the creature's spell fails and has no effect. That creature then has to make a CON save or be stunned until the end of their next turn. You also gain a spell slot level equal to the level of the spell countered, for the next hour.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the interrupted spell has no effect if its level is less than or equal to the level of the spell slot you used.

"As usual, my brother's maneuvers are brash and impulsive." - Urza