Cry of Insanity:
User can unleash a loud cry that can make any creature (human, animal, and even insects) that hears it go insane/berserk and attack whoever the user designates as a target. The cry will act like a steroid to boost the power, speed, agility, stamina, skill/quirk abilities of those that hear it exponentially. However, as a consequence for such a mad state the receiver's intelligence and rationale is lost. They will attack wildly and be completely unpredictable. Their nocireceptors (pain receptors) will also be turned off so they will be unable to feel pain of any kind.
Psychological quirks will also have no effect as they have no fear and run on instincts vs actually thinking their actions through. In addition, the receivers temporarily gain the ability to regenerate from injuries albeit gradually vs having super regeneration. This can help them keep going for an extensive amount of time. Moreover, cry of insanity's effects can last between 30 minutes to a full 3 hours depending on how much power was channeled to the scream.
Summation of power is also possible if the user screams again while all receivers are already under the quirk's influence. This will multiply the boosting effect proportional to how many times the user unleashes a cry (x 2 if they scream twice, etc). However, this will lead to a quicker onset of overuse effects.
Allies would require ear protection or quirks that can nullify sounds to not become affected by cry of insanity since the ability does not differentiate between friend and foe. Nonetheless, it can be an excellent ability to make enemies turn on their own comrades and to create chaos as a distraction or decoy tactics.
Drawbacks: sore throat, fatigue, and temporarily losing their voice/becoming mute.