Baleful Counterspell

You attempt to interrupt a creature in the process of casting a spell, and forcefully redirect the energy of their spell directly back into the body of said caster to painful effect. If the creature is casting a spell of 6th level or lower, its spell fails and has no effect, and the resulting creature suffers 3d12 force damage plus 1d6 of force damage for every level of the spell that was countered.

If the enemy 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. An attempt to Counterspell a Baleful Counterspell requires the ability check to exceed the level of Baleful Counterspell by two or more, or they suffer 1d12 force damage and are knocked prone from attempting to interfere with it and the spell is cast as normal.

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.