Flash Mob is an achievement that can only be won with the Necroa Virus DLC. How to get this achievement? Use the Zombie Horde ability at least once. It is extremely easy to unlock. Retrieved from "https://plagueinc.fandom.com/wiki/Flash_Mob?oldid=62650" Categories: Achievements Necroa Virus Active Abilities Community content is available under CC-BY-SA unless otherwise noted.