In Armored Core 6, players will eventually have to face off with the Sea Spider. A mysterious creation of the "Institute" that poses quite a threat and is possibly the most difficult encounter players will have faced up to this point. The Sea Spider arrives during the final mission of chapter 2, guarding the way to the Cargo Launcher.

The Sea Spider is fast and has access to a wide range of attacks, becoming even trickier to deal with during its second phase. With that in mind, here's how to beat Sea Spider in Armored Core 6.

Updated September 14th, 2023: The Sea Spider is a pretty imposing foe for AC6 players who are unprepared to deal with its punishing attacks. Those who attempt to beat the Sea Spider in Armored Core 6 without the proper setup or understanding of its attacks may find themselves restarting the boss fight over and over. To better help players understand the Sea Spider fight better in Armored Core 6, the following guide has been updated and now includes a video.

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Attacks

Phase 1

The Sea Spider mainly utilizes energy weapons in combat. It can fire a rotating barrage of lasers as it jumps and fire concentrated bursts from its turret while stationary or right as it lands. It can also charge up a beam that can sweep horizontally or vertically, which will deal immense damage if it connects. The rotating shot it fires mid-jump is best avoided by sticking close to the Sea Spider, and the concentrated bursts can be evaded using quick boost to move left or right.

When it begins charging a beam, players should watch for how it begins the attack. If it begins by aiming to the left or right of the player's location, it will perform a horizontal sweep that can be avoided by boosting into the air. Otherwise, it will use a vertical sweep, which can be dodged by boosting left or right. It will also sometimes charge up a bolt instead, which can be dodged the same way as the vertical sweep but will always be followed by a second bolt, necessitating a second dodge shortly after the first to evade both.

The Sea Spider will also fire bolts into the air that will rain back down after a delay. These are best avoided by staying on the move, as the Sea Spider's attacks do not have good homing.

The Sea Spider has a tremendously powerful melee attack, where it lunges forward and stabs downwards with laser blades that extend from its front legs. This can be avoided by quick boosting diagonally forwards so that the AC slips under the Spider and out to the side as it comes down. It can also be avoided by quick boosting backwards with similar timing. It can also perform a ground slam after hovering, which is best avoided by boosting away from it as soon as it starts to hover.

Phase 2

When the Sea Spider drops to roughly 1/3 of its health, it will take to the air and begin flying and spinning. During this phase, it will attack using a devastating laser blast that causes a huge explosion fired from its core. This can best be avoided by launching into the air or, ideally, being airborne when it fires.

It will also launch forwards while spinning its legs, emitting laser blades from each leg. This attack can be dodged by simply getting above the Sea Spider while it is doing that. Throughout this phase, the Sea Spider will also attack with laser fire, which can be avoided by staying on the move, either on the ground or in the air.

Strategy (How to Beat Sea Spider in Armored Core 6)

The Sea Spider is best fought with Tetrapod Legs, allowing the player to take advantage of their air superiority to rain attacks down on the Spider, especially during phase 2. Reverse Joint Legs and a lightweight AC can also work well here, though they'll be on the ground a lot more and thus in range of some of the Sea Spider's more dangerous attacks. A reasonably fast AC is very helpful in this fight.

The Sea Spider is very vulnerable to ACS Strain, which can be exploited by loading up SONGBIRDS grenade launchers or a 10-cell missile launcher on the AC's shoulders. Explosive weaponry in the right hand is also very effective for this purpose. Once staggered, melee is the way to go to dish out the most damage. Laser Blades can be very effective at this, as can Pile Bunkers. This strategy works well in both phases, using explosive weaponry to stagger the Spider and then pounding it in melee combat.

Best Sea Spider Build

For this fight, players are going to want the Tetrapod Legs and some explosives. The SONGBIRDS grenade launchers are the single best option for inflicting ACS strain on the Sea Spider and Staggering it. Paired with the ASHMEAD Pile Bunker for dishing out some serious damage once staggered, this setup will tear through the Sea Spider's health.

Here's an example build that handles Sea Spider well:

Armored Core 6 is available for PS4, PS5, PC, Xbox One, and Xbox Series X/S.