Backlash

You disrupt and cause the spell of a creature in the process of casting a spell, to backlash. Depending on the spell cast, different outcomes may occur. If the creature is casting a harmful or debilitating spell of equal level, 3rd level or lower, it instead targets the caster using their own spell save DC and/or modifier. If the creature is casting a harmless, helpful or empowering spell of equal level, 3rd level or lower, it instead targets and/or affects you, ignoring the range of the spell. If it 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 either targets the caster using their own spell save DC and/or modifier or targets and affects you, ignoring the range of the spell. Should any of the spells have concentration, the caster still maintains it. A backlashed spell that involves a command or changing of forms the will happen as the original caster intended (A Backlashed Command will be the command of the caster. A Backlashed Polymorph will turn the target into the intended form of the caster).

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the backlashed spell has no effect if its level is less than or equal to the level of the spell slot you used.