Zombie Pods

Zombie Pods is the fourth mission in. The primary objective is to destroy all zombie pods on the map. It is also arguably the best mission for getting many strongboxes on, with many guaranteed loot spots, about 6, 2 at spawn, 2 in a hidden room, 1 in a hidden spot and 1 near the boss room.

Plot
A digital strain of the zombie virus has taken over Combot and created cyborg zombies. Humans and robotic components are being harvested into egg-like pods. This map is most likely intended for the first encounter with the Zombie Mech (although ironically you can encounter the mech in earlier levels without ever playing this one by avoiding it until after level 20).

Layout
The starting area is a parking lot, where the objective is to destroy all the zombie pods, including the zombies inside, in the parking lot. Then, a horde of zombies breaks down the entrance from the inside of the supermarket, though you can also destroy the entrance.

There are a total of four Purge Nests inside the supermarket, which each spawn a group of zombies every thirty seconds, and will only spawn zombies once approached. It is the player(s)' objective to destroy all the Purge Nests. Besides Purge Nests, the supermarket also has zombies and zombie pods inside of them as well as cash registers that can be shot at for SAS Creds.

After all the Purge Nests have been eradicated, a passageway to a much larger parking lot is opened. The market is blocked off, too, so the player can't go into the market for defense. This vast area is where the boss spawns. Many zombie pods are scattered throughout the parking lot, as well as four mutated pods, called Minion Eggs, surrounding a much larger zombie pod, the Boss Egg. Upon approaching or shooting the Boss Egg, it will appear to create temporary spikes over a large area in defense. The spikes can be deadly and potentially can kill a player under it in one hit. Unlike the one or two zombies that emerge from each regular zombie pod, a group of Runners, Spitters and Bloater(s) emerge upon destroying each Minion Egg. Breaking the Boss Egg releases the boss as well as break open any Minion Eggs that haven't yet been destroyed. Throughout the entire fight, groups of weaker zombies will spawn from the "caves" inside the walls.

Once the boss has been defeated, groups of zombies will continue to spawn from the walls, though a twenty-second countdown is initiated before the game ends in a victory.

Loot

 * By shooting top wall of starting point, two pods, a group of zombies, and loot will be revealed in a room behind.
 * Above the gateway, there's loot protected by 2 pods.
 * All 4 cash registers contain a money amount, depending on player's level. This does not count towards loots for High Damage Ammo via Field Supplies Skill.
 * There is loot found by destroying the shelf below the top right purge nest.
 * Beside the passage before the boss area, there is a door you can enter for 2 loots with 3 pods, in Nightmare Mode those worms will be Nightmarish, so be careful or you will die.
 * In the boss area, there's a passageway to loot in the top left corner.
 * All pods have quite a high possibility to contain loots.

Tactics
This is one of the easiest maps among players, with the most loot on top of that. Due to the fact that purge nests grow significantly stronger with every couple of spawns (from spawning normal Apex Runners to Regenerating Bloaters), rushing ahead would likely result in failure as getting close to the nests will trigger them to spawn. If all four nests are spawning, it is extremely dangerous as by the time players reach the fourth nest, it will begin spawning multiple resistance Bloaters. However, this may be used to farm kills for bounty awards if players are confident in their ability.

The boss room at the end is huge compared to other boss areas, but due to the number of zombies that spawn from the walls, there are considerably fewer safe areas to regenerate health or think about strategy. Running to the secret stash in the boss area during the boss fight will trap the player in with the boss(es) if he does not move out into the main area in time. It is advised to destroy the normal pods first so that a misfire when focusing on minion eggs or zombies will not trigger sudden zombie spawns.

When first entering the boss room, it is a good idea to destroy the Minion Eggs one by one, then just wait for the Boss Egg to open itself, since the player(s) will have fewer zombies to deal with during the boss fight. In Multiplayer, the spikes the Boss Egg shoots out deal substantial damage to most players, so people playing together can communicate to not shoot or go near the Boss Egg.

The alternative is to focus on the boss egg (which will also get you the Precision achievement). Upon destroying it, all minion eggs will burst and spawn mass of zombies, but can easily be dealt with with a Strike team, Antidote bomb, Aerial Bombardment, or otherwise any weapons with great hording ability.

Map Specific Achievements

 * Precision
 * Map Master - Pods

Trivia

 * Zombie Pods is the shortest level in the game; speed runs have been clocked at under a minute, the record being under 40 seconds.
 * In a CSV file of the mobile version's game file, a mysterious, unused dialogue message for this mission exists: "Cleanse biothreat... SAS squad... Continue iteration of biomatter incubation... Perfection can be achieved..." The message is called "Start," which, going by other dialogue messages in the file, would mean this message would appear at the beginning of the mission. As for the speaker, it would seem that it is Combot.
 * As the player is halfway down the hallway to the last Purge Nest before reaching the boss area, he will say "Hey, they still have twinkies here, not even Zombies will eat these", which is a reference to Zombieland.
 * Two major updates have taken place for this mission. The first, in the Private Matches update, caused the entrance to break down after a period of time, meaning players no longer have to destroy it manually. The second change, where the boss egg would attack when a minion egg is destroyed, was undone on October 8, 2014, and the Boss Egg will no longer get provoked by the destruction of a Minion Egg (this wasn't mentioned in the update history).
 * On The mobile port of SAS 4 the boss egg can become provoked by destroying normal eggs without even harming minion eggs nor the boss egg.
 * This level features two examples of "dynamic loading":
 * One, when using a Gigavolt or other arcing weapons, you can pre-detonate the pods in the hidden room on the upper area of spawn. However, the other zombies that spawn there will not appear until you actually break the wall.
 * The second can be experienced with a faster character, if that character is to walk speedily into the encounter room, they will momentarily see an absence of pods, which will appear almost immediately afterward.
 * It’s the only level containing Shopping Trolleys.