- CF China: Altar Trial.
- CF N. America: Deadly Tower.
- CF Vietnam: Tower of Death.
- CF Russia: Citadel
- CF Japan: Deadly Cliff
- CF Brazil: Deadly Tower
- CF Español: Deadly Cliff
- CF Europe: Deadly Tower
- SWATs busting into the tower wielding M4 Commando, ready to fight off any intruders. As they notice, hell has frozen over this entire floor and they are prepared for a cold reception:
|Frost Bite: These rabid mechanical dogs are fast; as they charge directly towards the soldiers. Their health points are moderate and can be easily killed.|
|Frost Subject: They are fairly similar to Dreads, they have long claws and move rather slowly. When killed, their body produces a small frozen pond that temporarily harms soldiers.|
|Baby Beast: These creatures are quite slow on the floor, but they can jump on the ceiling and move slightly faster in an attempt to charge at the soldiers from above.|
|Glacial Beast: The main boss of this floor. Like its beast counterpart, it can jump on the ceiling targeting a specific soldier. Otherwise he throws a bunch of ice around, while leaving frozen trails near him.|
|DMD: Returning from Thunder Tower, they spawn from one side of the room and attempt to reach the opposite side. If this happen, this will result in the entire floor being electrocuted, damaging all soldiers for a brief moment.|
|Destructor: Returning from Thunder Tower as well, although not on rails this time. These exploding bots, now freely roaming around the floor, serve as distraction to prevent soldiers from shooting the DMD mechs.|
|Machine Geckos: They hang on the honeycomb-like ceiling in this floor, jumping around to dodge soldiers' bullet and spit energy ball to hit them.|
|Machine Gargoyle: The main boss of the second floor. He can fly around and slash soldiers, use sonic-wave attack to sweep multiple targets, or go into defence mode and leave the fighting to his minions.|
|Fire Speedilos: Returning from Devastated City. These armadillo enemies have more health points and rolls faster than their original counterpart.|
|Magma Demolishers: Returning from Broken Station, this variant does not uses shields. However, they do charge at the soldiers and also attempt to hit them when nearby.|
|Blasters: Returning from Battleship, this variant uses C4 explosives instead of baton. They run around the floor tossing a bunch of C4s with short timer in an attempt to catch soldiers off-guard.|
|Persona: The main boss of the third floor. He's the most deadly one with his Blade and Molotov attack.|
In Hard difficulty onward, after beating Persona, the elevator will drop down back to the first floor, where soldiers will have to battle the former bosses and Persona again one more time to win - they have increased health points and use more deadly attack this time, making it quite hard to survive with minimal casualties.
The number of re-fight rounds depends on the difficulty setting, with Nightmare having players battling ALL bosses, including Persona twice. This makes the game twice as long, but the reward crates are also doubled.
Tips and Strategies
It is best to play with the "5x Sentry Gun" tactic since they cause high damages to the boss and help the players to kill the NPCs. If there's a lack of Hypomeds and/or Revival Tokens, one person could carry a Health Flag to recover health for the entire team.
- Shoot the top part of its iceberg to cause more damages.
- After the opening cut-scene, quickly place 2 Sentry Guns on the two small entrances that sided to the big entrance in the middle on both sides (one each) and have one person guarding them. Place 2-3 Sentry Guns in the middle where the big entrance is and have the rest guarding it. The small horde (of each small entrance) will only come out once each round (except round 4) so when they are all killed, the two people should join the big entrance (and later on get back to their old position for the next round).
- Before round 4 (when the boss appeared), everyone's Sentry Guns now should have been ready to use again so place them equally to form a big enough circle in the middle. No one should be running out of the circle and one person could attract the boss to make it stands still for easier shooting. The Health Flag holder could now place the flag to heal the person whose being killed by the boss.
- In the re-fight round, either apply the same tactic or place all Sentry Guns near the north entrance to kill off the Baby Beast. One person can stand still so the boss will also stand still while the rest stay behind and shoot it. Take turn while the other are respawning.
- After moving up from the Cryogenic Chamber, quickly place 2-3 Sentry Guns on each side of the tower (where the robots spawn). Prevent them from reaching the power center (on both sides too). One person keeping an eye on them on each side is enough.
- Same with round 4, apply the same tactic but this time since the boss can give out wide lines of plasma laser, you can jump on the Sentry Gun and then jump another time to dodge the laser easily (without having to decide whether to sit down or jump up).
- When the boss goes up to a platform to stand (still), the DMD (white robots) will spawn, have one person guarding each spawn place.
- Apply the same tactic before in the re-fight round
- From this floor, it is recommended to save your HypoMed as you will recover your HP fully in the bonus round. Try only to use the small HypoMed if really needed.
- After moving up from the Fusion Reactor, place all Sentry Guns close to the north entrance (where most AIs will spawn from). AIs will be spawning from other entrances as well but one person is enough to kill them.
- In the bonus round, all Sentry Guns should be ready to use again but place them after halfway of the round to help shooting any AIs and so that it is ready for the boss next round.
- Magma Demolisher will have significantly less HP during the bonus round.
- During the bonus round, everyone should be shooting at the north entrance. When AIs from other entrances starting to appear on the map (as red dots), each entrance should have one person. The unassigned entrance person can go and help to kill off any AIs as the penguin advances around.
- Same with round 4 and 8, apply the same tactic.
- When the boss is about to blow fire, focus shooting on its head, use AI grenade or the special PVE function of anti-zombie weapons (such as AA-12-Buster or M240B-Tesla). If still cannot prevent him from using that attack, run away far immediately.
- In the re-fight round, the boss can throw bombs that will cause 1/3 of the floor to be covered in fire, he won't throw on where he is standing.
- When the round started, everyone should be close to the south entrance (farthest away from where he entered from) and place the Sentry Guns there. This is because when a person died, he/she will respawn there which will make the boss change his target as he/she has more HP, run to it and away from the Sentry Guns, making it useless.
- Occasionally, he will throw gasoline bomb on a target. But when he came on, he will throw it to the furthest people away which help to dodge it easier.