You attempt to interrupt a creature in the process of casting a spell by directly countering the school of magic they use. When you cast this spell, you choose what school of magic it is. If, according to the table below, the school of magic you chose opposes the school of magic of the creature’s spell, it’s spell fails and has no effect, if said spell is of 3rd level or lower. If the creature is casting a spell of 4th 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.

At Higher Levels. When you cast this spell using a spell slot of 4th 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.