Securement Silo Theta walkthrough - Once Human - Upcomer
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A player in Once Human defeating the boss and clearing Securement Silo Theta, with a victory message on-screen.
Screenshot by Upcomer

Securement Silo Theta walkthrough – Once Human

Securement Silo Theta is no walk in the park. The final boss isn’t too bad, but the secret boss is pretty tough. At least, that’s what I found. The only complication to the final boss is the immunity he gains, but it’s all explained in this guide.

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From the puzzle room to all the loot locations, this post will walk you through the entirety of Securement Silo Theta.

Enjoy.

Where is Securement Silo Theta?

Securement Silo Theta location displayed on a map and marked with an arrow in Once Human.
Screenshot by Upcomer

Securement Silo Theta is in Red Sands (5535,-514). It’s nearby the Blackfell Oil Fields, and also has a handy nearby teleportation tower in order to get there fast. You might want to bring some Malt beer or Corn ale with you, since there’s plenty of potential sanity drop in this dungeon.

You’ll also benefit from having a few long-acting Activators on hand, just in case.

What can you get in Securement Silo Theta?

Securement Silo Theta drops Legendary Chest mods, with the chance to obtain more at higher difficulty levels. You’ll also get stardust source, energy links, armor mod parts, and any crate contents and materials you find inside.

Rewards also include a weapon of Epic or Legendary rarity (when using a controller). Always use a controller in these dungeons when farming for specific gear!

How to clear Securement Silo Theta

On spawning in, you won’t find any loot crates or materials for a while, so just carry on and glide down to the actual start of the dungeon. You’ll enter a sewer that goes both right and left. Kill the enemies on your right before heading down the tunnel on your left.

Be careful not to step on the black sludge down the middle of the sewers, as this will drop your sanity.

Down this tunnel you’ll find some more enemies, including a Gasbag if you’re playing on Hard or Pro. You’ll also find a storage crate and some materials. Keep going, and be sure to collect anything you find on the way.

You’ll reach a spot with loads of enemies, which is a four-way crossing. They vary by difficulty, but you’ll always have a few more Gnawers spawn in, so stay alert.

Player running towards enemies in a sewer in Securement Silo Theta.
Screenshot by Upcomer

Turn right here for another storage chest, container, and materials. Straight you’ll find some more materials, but ultimately you’ll have to take the left route and keep going, with more things to pick up here.

The first left you can take leads to a storage chest, and you’ll have to step ion the black goop to get it. Just a little tip, if you put pure water and wheat or corn in a brewing barrel, you’ll get a drink that keeps your sanity from dropping for thirty minutes – it’s quite useful in Securement Silo Theta.

Carry on the way you were going and all the way to the end of the sewer for more materials and a loot container. When you’re done, head up the stairs you passed (they’re to your right near the end of the sewer).

An arrow highlights the stairs in t he sewer that lead to the next area of Securement Silo Theta.
Screenshot by Upcomer

The next room you enter will have a fair amount of enemies. You’ll have to clear all the Nest sacs in order to move on. Once cleared, you can collect some loot in this room. There’s also a few storage chests above, which you can reach by climbing the ladder in the black sludge in the center of the room.

When you’ve grabbed everything, it’s time to face the secret boss.

The puzzle and secret boss at Securement Silo Theta

From the room where you had to eliminate the Nest sacs, look for the door that has torn material around it. It looks like this:

The door that leads to the secret boss in Securement Silo Theta in Once Human, marked by an arrow.
Screenshot by Upcomer

Head inside, grab the crates, and then rotate the statue once to pass through the Seepage zone. You’ll come across a room filled with statues and a monster under the water. The trick is to rotate all the statues so their reflections match up.

A player solves the statue puzzle in Securement Silo Theta and summons the secret boss.
Screenshot by Upcomer

Once they do, you’ll be fighting a pretty powerful enemy with plenty of additional monsters around (on Hard and Pro). It’s a challenging fight, be prepared. If the enemy lives long enough, he’ll spawn a barrier around him that inflicts toxic damage on you, so try to take him out quickly.

Grab your reward, and head back. Before you turn the first statue to leave, grab another crate in that room and some materials.

Back in the room with the Nest sacs, take a right and head onwards. You’ll need to navigate those annoying spitting mouth traps on your way through. Enemies do spawn in here on higher difficulties, so be on your guard.

The next room offers some parkour to get additional crates, and the higher difficulties have more of the spitting mouth traps, so take it slow (you don’t want to end up on the black goop below and lose your sanity).

Walk along the top and head through the tunnel to face the final boss.

The tunnel that leads to the final boss at Securement Silo Theta highlighted by an arrow as the player runs towards it.
Screenshot by Upcomer

Beating the boss at Securement Silo Theta

There’s not much to say here. It’s a Glutton — nothing we haven’t faced before. There are some enemies in the room I like to take out before I enter it though. Simply hit the Glutton’s weak spots on his legs, and when he drops, burst him down.

There is one catch to this boss though. He gains immunity and spawns puff ball spores, which you have to take out in order to damage him again. You’ll need to hurry as well, since the room will fill with poison mist and deal damage to you.

A player destroys puffball spores in green mist while fighting the boss at Securement Silo Theta in Once Human.
Screenshot by Upcomer

A long-Acting Activator can be very useful here, especially if you’ve opted for a glass cannon build (like me) and you can’t soak up much damage.

From where you entered, one spore spawns near the center of the room, right near where Saint El (the boss) spawns in. There’s another puffball spore in the far right-side corner, and the last one is near the far left-hand corner.

You’re likely to have to find more on Pro, and their locations may even be randomized. They’re not hard to spot though, since they glow through the mist and the mist itself is a lot less dense that that of the Arachsiam boss (thank goodness for that!).

And that’s all there is to it. Burst Saint El down, grab your rewards, and loot this room before you leave. There are a number of storage crates and containers to get.

A player in Once Human defeating the boss and clearing Securement Silo Theta, with a victory message on-screen.
Screenshot by Upcomer

I’ve done guides on all the Securement Silos, so if you need help with any of the others, choose your next guide below.

If you have any trouble here, I have a full guide on the Shrapnel Build that’ll make you more powerful in Once Human.

Author
Image of Kyle Ferreira
Kyle Ferreira
As the content manager at Upcomer, Kyle brings a lifetime of gaming and over seven years of professional writing experience to the platform. He holds a tender spot for indie games, but can sometimes be found in an FPS getting destroyed in a fruitless attempt to relive his old CS 1.6 glory days. After which he can usually be found licking his wounds in a chill game of Kenshi.