Destroy Magic

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 6th level or lower the spell fails and has no effect. If the creature is casting a spell of 7th level or higher, make an ability check. The DC equals 10 + the spells’s level. On a success, the creature’s spell fails and has no effect.

If the spell is interrupted the caster must also make a wisdom saving throw. On a failed save the creature takes 2d6 psychic damage and forgets how to cast the interrupted spell for 5 days. On a save, the creature takes half damage but doesn’t forget the spell they cast.