Duou

Summary
Duou is an alternative combat spell using soundwaves to disrupt, damage, cripple or kill opponents. The sound comes in three 2 second long screeches, each louder than the last. The first screech is 105 decibels, the equivalent of the max volume of headphones. The second screech is 150 decibels, equal to a gunshot and can cause hearing damage. The final screech is 220 decibels, enough to kill a normal human and louder than a sonic boom. The caster of the spell is immune to the effects, but everyone else around them will hear it as it is not targetable.

Uses
Duou is usually used in duels between mages as a way to bypass shields, or as a way to fight multiple enemies at once. For obvious reasons, it is useless when fighting with allies or for stealth. The spell is also easily countered by the other mage casting it as well, as both mages would then be immune.