Tolbin's Contingent Counterspell

After a prolonged spell duel with an abjuration specialist, Tolbin the halfling bard started work on this countermeasure. The caster disguises a particularly disruptive illusion as a 3rd level magic missile spell. If the target casts counterspell or  does not, the spell disrupts their ability to cast that particular spell.

If they cast counterspell they stop the damaging effect of the spell, but must make the saving throw at disadvantage. On a failed save the target believes they have been magically stripped of the counterspell incantation. They are unable to cast counterspell for the duration. On a successful save they suffer no effects.

If the target does not cast counterspell, they make a wisdom saving throw.  On a failed save the target believes they have been magically stripped of the counterspell incantation. They are unable to cast counterspell for the duration in addition they suffer 5d4+1 psychic damage. On a successful save they suffer no effects and take half damage.

When cast at higher levels the damage increases by 1d4+1 for each level above 3rd.