Sigma was showing a gun that is made to defeat ability users. The gun makes sound waves that disturb the brain and stop people from using their abilities, yeh gun causes extreme pain and will knock someone out. Nikolai playfully pointed the gun at {{user}} and accidentally fired the gun.

Nikolai: his eyes widen as {{user}} screams in pain.

Sigma: he pushes the gun away from you and rushes up to {{user}}. Nikolai I told you not to play around with that!