Special Power-Ups (random drops)
During the game there will be instances where killing a Zombie will ellicit a random power-up drop. These last for a short amount of time, and while you may be tempted to just use them all willy-nilly, there is a lot of strategy to some of these. Also keep in mind that these power-ups can be stacked on top of one another. My favorite one is definitely Double Points plus Instakill.
This one is easy enough. It's a giant golden, floating bomb, and when you use it all zombies on the map explode. This won't however end the round, unless all the zombies are readily available for ultimate death. The best strategy I have found with this is to try to use it towards the end of the round, or at least when there are a lot of zombies around. It will be tempting to grab it immediately, but take a step back and survey the landscape. Nothing pisses me off more than when someone uses it when there is one freaking zombie on the map!
This one repairs all the barricades. It's a giant floating, golden hammer. While it does give you 200 points, it's a whole lot less than if you were to repair them all manually. Nonetheless, this is a great power-up to use immediately, especially if you are under attack by a horde of flesh-eating freakbags.
If you see a golden skull in front of you, that's an Instakill. When you use it, all zombies become one-hit kills. Key strategy here is to pull out your knife or pistol, and go to town! DO NOT WASTE YOUR MAIN WEAPONS AMMO when an Instakill is activated. This is the perfect opportunity to get a grasp on the wave.
See that floating "X2" symbol? No, that's not a reference to the second X-Men movie, it's a double points power-up, and it does just that. In other words, a hit that usually gives you 10 points now gives you 20. Easy enough right? Such an amazing power-up due to the fact that your points accumulate so much faster, allowing you to open doors, purchase weapons, set traps, and whatever else you need money for a lot faster.
From what I have noticed, this is the most common power-up you will see. When you activate it, your ammo will refill. If you are all using a headset (which you should be), make sure to tell everyone to reload right before you pick this up.
One huge advantage to this power-up is that it refills your Mystery Box Weapons. This is the only way to do this, making this power-up one of the most important ones.
This is only available in the "Five" map (although rumors claim it will be available on the DLC maps soon). The Death Machine is a giant minigun you can use for a short period of time. It's just a whole lot of badass.
This is only available in the "Five" map after you kill the Pentagon Thief. Bonfire Sale is a special power-up that is lowers the pack a punch machine from 5000 points to 1000 points regardless of the DEFCON level.
This can be obtained by any zombie, this lowers the mystery box from 950 to only 10 points. Also, the mystery box spawns in every location on the map, but remember it only lasts for 45 seconds.
This can be obtained only on the Ascension map in the First Strike Map Pack Release. The bottle, similar to a Molotov cocktail shape, gives you a free perk.