Defeating Arachsiam Once Human
Image: YouTube Project

Once Human Arachsiam Great One walkthrough and boss guide

Eight legged freak.

Defeating the Arachsiam in Once Human takes quite a bit of skill and a pretty high level. It is no easy fight, and if you’re scared of spiders, I would just skip it altogether.

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How to beat Arachsiam in Once Human

First, make sure you’re around level 30 before going into this fight. Also, make sure you have some high-level weapons equipped. If you’re still lacking on the levels and gear side, try taking down Rabizex first. It’s an easier fight and will help you get to where you need to be.

Arachsiam’s location in Once Human

Before you try and fight Arachsiam in Once Human, you will need to be in the Iron River area of the game. This is just north of the Dayton Wetlands, where you first fought the Foul Shadowhunter. As this is a storyline boss, the story quest will guide you on how to unlock the Rift Anchor for Arachsiam.

Mirage Monolith Location Once Human
Screenshot: PC Invasion

Once you have loaded both the Rift Anchors with the required materials, the Great Rift will be open, and you can enter. This area is called the Mirage Monolith and is located in the north of the Iron River area. This will drop you into the location for the Arachsiam Great One battle in Once Human.

Before you start this fight, I recommend being at least level 30 or close to it. The more of you heading in, the better. Two players is a good amount, but more stand a better chance.

For this fight, tier-three weapons are a good place to start. For the best results, try to get some kind of assault rifle, like the AK or the Scar. Both of these will have the range you need to hit the weak spots on this very large enemy and also take down the eggs during the defense stage. What you want is good medium to long range and a high fire rate. I would not recommend short-range at all.

For your secondary weapon, a sniper rifle is a great choice. Some of the eggs Arachsiam drops are quite far, so this will save you the time needed to run over to them in the Arachsiam Once Human boss fight.

Damage stage

Once you have made your way into the lair of the Arachsiam in Once Human, make sure you maintain distance from it. She has a melee attack that is absolutely devastating if you are in range, so stay far back. Immediately start unloading your weapon into her weak points, which are her head and the green venom sack on her body.

Defeating Arachsiam Once Human Walkthrough
Screenshot: YouTube Project

Now that you have started the fight, there are a few attacks you should be aware of before she enters the defense stage. The first is the projectile web, which will shoot out and pull you in. The second is a ground slam.

However, both of these are telegraphed by her raising both front feet into the air. As soon as you see this happen, stop shooting and start running to the left or right. They can be avoided easily like this.

Continue to unload your weapon from a distance into the weak spots. Eventually, you will drop down the Arachsiam health far enough to enter the next stage of this Once Human boss fight. The next stage will be signaled by the arena filling with mist.

Defense stage

This stage will be a little tricky to see anything in. At this point in the fight, Arachsiam drops eggs that constantly spawn exploding spiders until they are destroyed. These are dotted all over the place and need to be sought out and shot.

Arachsiam Once Human Walkthrough
Screenshot: YouTube Project

To locate the spider eggs in the mist, simply look for their purple glowing signals. This light will shine through the mist, showing you where to shoot. I would suggest using your sniper at this point to avoid having to run through the mist to each location.

During this stage, Arachsiam can still attack, so don’t stand still for too long, or the melee or web attack will get you. It is impossible to attack Arachsiam in Once Human until the eggs have been destroyed. Once they are all gone, it is time to go back to the damage stage and rinse and repeat.

Be aware of the eggs she will continue to drop around the arena. Take them out as often as you can, or you will be quickly overwhelmed.

Arachsiam rewards

As usual, when killing this enemy, you will receive a whole load of loot, including Energy Links, weapons, weapon mods, and, of course, Stardust. If this is your first playthrough, make sure you also pick up your Deviant as well.

Dreamcatcher Once Human Deviant
Screenshot: YouTube Mr Jeast

The Once Human Deviant picked up from the Arachsiam fight is called the Dreamcatcher. This Deviant, when kept in your territory, will help you recover your sanity when you sleep close to it. This is a great buff, especially if you’re suffering from low sanity. This Deviant likes blue lights, relaxing music, and low temperatures. It does not like animals, so keep them away from it to reap the benefits of this Deviant.

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Leo Gillick
Leo is a Freelance Writer for PC Invasion. He has a degree in English Literature and Film Studies and more hours buried into videogames than he cares to admit. He has worked extensively in the Videogame and Travel writing industry but, as they say, get a job doing something you love and you'll never work a day in your life. He uses his writing as a means to support indefinite global travel with the current five year plan seeing him through Latin America.