Deep underground the Harvesters build the military outposts of their empire. Filled with their constructs, they are truly dangerous places.
Deep underground, Harvesters created large militaristic bases to further their plans. Long since abandoned for unknown reasons, the Underground Base is full of Harvester constructs, with purposes from defense to offense. Sentries walk down halls, ready to fire at any detected threats, Fire Beams rain down molten metal on any intruders, and Securon controls it all behind the scenes, ready to defend the base from the Shells of Eschaton.
Being a military outpost of a very advanced civilization, lots of rare and great items can be found within. In fact, there's rumours of a hidden merchant who sells very rare items... for a price. However, damage output is high, and Rocketeers, Walkers, and Securon can wipe out groups in minutes if they're not careful or properly geared. It's a true test of skill!
The Underground Base can be accessed by any one of its numerous doorways in Eschaton.
The boss of the Underground Base is commonly known to players as Securon. Its room consists open space in the center, platforms at different heights by either side, moving platforms on the inner side of these, and teleporters on each from the floor to a high platform.
As players enter the boss room, a single Heavy Mech is on the floor. After this enemy is killed, the actual boss fight begins. The boss fight cycles between two parts: the boss phase, and the spawn phase.
During the boss phase, Securon itself (a large rectangular enemy) comes down. It moves around, attacking players by shooting streams of bullets from its sides, releasing red bombs of multiple sizes, and hitting into players. Its attacks become more frequent and dangerous as the boss fight goes on. Additionally, the boss starts with armor; later on, the boss loses its armor and exposes an eye, which (alongside some fakes), telegraphs it movement. With full damage, this happens on the third time the boss is down.
During the spawn phase, the boss drops into the background. Enemies spawn along both the floor and the platforms- though not on the moving platforms. As the boss fight progresses, this phase spawns more enemies and passes by in a shorter amount of time.
If full damage is done to the boss, there will be a total of 5 boss phases, with 4 spawn phases in between them. The boss itself will die at the end of the last boss phase.
The boss can drop any standard tier three equipment up to Experimental level. Additionally, it drops the following exotic equipment: Dragoon, Balefire Skein, Mirrored Warp, Swarmer and Stompers.
There are two secrets in The Underground Base. One is accessed by an invisible hole in the side of a wall. The other is a secret shop found by activating an Z in the corner of a path. This will open up a teleport that will warp one to another exit leading to the shop. The secret/shop tends to be found AFTER the midboss. However, in the case the midboss does not exist (and sometimes that happens), the secret/shop tends to be hiding near the boss room. The secret contains EC or stat boosts, along with one exotic item. In the elite variant, the exotic item will have one modifier.