Every 15 seconds or every time you get an elimination or die, you will get a random effect.
Over 100 possible effects, including stat upgrades like increased damage/speed, being teleported around, getting aimbot, spawning a giant bomb, putting enemies to sleep by doing damage, pulling enemies towards you, and a whole lot more!
Have fun and enjoy the chaos! You will die a lot in this mode, but that's part of the fun. It just gives you more effects!