[quote=@Lacroix] The magical sound waves disrupt and erode any form of conjured magic in their path, making it harder for them to mantain their form. As such, Nightmares would be slowly weakened and damaged, projectiles made with magic would lose a bit of strength and objects created with magic would be damaged little by little until they break, unless one invests energy to help them mantain their form. Against other magical girls it's loud and disorientating but, unless they're caught by it by prolonged periods of time, there's no real damage to them, their arms nor their emblems. [/quote] That's pretty much alright, except for the part of it having the chance of damaging permanent magical effects like the girl's weapons and Emblems. Make it so that she can only disrupt transient magic and she'll be alright.