Attackaport

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 4th level or lower, or makes a ranged attack, the spell or attack gets teleported, making them the new target. If it is casting a spell of 5th level or higher, make an ability check using your spellcasting ability. The DC equals 14 + the difference of the level of the spell and this one. On a success, the creature's spell gets teleported, making them the new target.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the spell gets teleported, making the caster the new target, if its level is less than or equal to the level of the spell slot you used.