Power-Ups are unique perks that grant powerful bonuses in Zombies Mode. These bonuses include increased essence gain, insta-kill effects, max ammo, and even the ability to grant random Perk-a-Colas. In most cases, Power-Ups will have a chance to spawn randomly for a brief peroid of time after defeating Zombies--if you're not quick enough, they'll disappear before you can claim them. It's worth...