Katsuki creates a sphere of light between his hands that explodes into a large scale flash. Similarly to the effect of an actual stun grenade, the flash of light blinds anyone close by.
It is especially effective against Quirks that are weak against light, such as Fumikage Tokoyami's Dark Shadow. Katsuki first uses this move to overpower Fumikage during the U.A. Sports Festival. He also used it during the First Term Final Exam against All Might , and then again during his fight with Izuku .
- The animation for using Stun Grenade bares a striking resemblance to the Final Flash attack from the Dragon Ball series.
- Stun grenade - Wikipedia article about the weapon that inspired this Super Move.