Plays a relatively loud, high-pitched annoying 10-secs long screech when you're about to get AFK Kicked from a game. Type '/omgstop' to make it stop
Plays a sound when you kill someone in skywars or the pit.

Guide to changing sound: https://hypixel.net/threads/ct-killsound-play-a-user-defined-sound-when-you-kill-someone.1743276/