Armored Core 6 Sea Spider boss guide – how to beat the Sea Spider in AC 6

Stuck trying to beat the Sea Spider in Armored Core 6? There are plenty of tough bosses in Armored Core 6 Fires of Rubicon, and the Sea Spider definitely qualifies for the honour. Enormous, aggressive, and armed with devastating, Coral-powered attacks, this monstrous creation can easily make short work of the unprepared.

Here, we’ll cover the best strategies and tips to help you beat the Sea Spider in Armored Core 6. You’ll have already fought against the likes of Balteus, the Smart Cleaner, and Sulla to get this far. You can pull this victory off too. But in case you haven’t beaten them all and just stumbled across this guide by happy accident, check out our advice on those bosses too if you’re stuck.

How to defeat the Sea Spider in Fires of Rubicon

Here are our best tips for beating the Sea Spider in Armored Core 6.

• Build for long range.
• Keep distance and use flight.
• Learn how to handle the deadliest attacks.
• Maintain a consistent damage stream.
• Use your repair kits strategically.

If you’re able to utilise all this advice well, you should find that your experience against this boss rapidly improves. Let’s go over each tip in a bit more detail.

Build for long range

There are a variety of ways to handle any boss, but the Armored Core series is still fond of encouraging players to diversify their mech builds and try new strategies. This is no less true for the Sea Spider. This boss is aggressive, and deceptively well defended. At close range, getting caught by a melee attack can cost you a massive chunk of health, and dodging its powerful cannon blasts is extremely challenging. Worst by far though is its machine gun bursts.

The Sea Spider can launch these bursts from any point around itself, utilising the attack as something of an anti-personnel manoeuvre. It’s possible to avoid the worst of this with dedicated side-dodging at memorised timings, but not easy. What really makes this move so dangerous is how quickly it can stun you. Taken with the rest of the moveset, this makes it relatively easy for the Sea Spider to stunlock players as soon as they make a mistake.

What all of this ultimately means is that you’re far better off designing your AC for a long range engagement. The only time you should aim to rely on melee or close range in this fight is for damage dealing when the Sea Spider is stunned – but make sure you’re confident with your positioning and speed if you’re set on using this tactic. As the melee options you’ll lose out on provide good stunning benefits, be sure to replace them with high-damage, posture-breaking armaments. Grenade launchers, rockets, laser cannons and rapid-fire missile launchers are all good choices.

Keep your distance and use flight

Once you’ve got your AC reworked to a build you’re comfortable with, remember to maintain that range. At long range, the most potent attacks of the Sea Spider are much easier to avoid. You can dodge, or even use cover in the arena to block some of the worst. More importantly, distance gives your own posture bar time to decrease after taking damage. This is important, as a successful stun by the boss will allow it to close distance quickly.

Remember to use flight as much as you can too though. In the first phase, this leaves the Sea Spider unable to reach you with most attacks, and gives you fantastic opportunities to maximise your damage output. In the second phase, flight creates additional distance from the Sea Spider’s devastating AOE explosions, a moveset you’ll want to avoid at all costs.

Learn how to handle the deadliest attacks

As mentioned, the Sea Spider packs a few devastating attacks which can easily cut a run short. Being able to deal with these moves drastically improves your survivability. Here are the top moves to watch for, and how to counter them.

Coral cannon shots

The Sea Spider will fire two to four shots from its topside cannon, each dealing high damage on impact. Dodging is the best counter here. Slow down when you see the powerup which telegraphs this attack – you’ll need spare energy to pull off these dodges. Aim to time each dodge so that you’re executing the move within the first second of the shot firing – moving earlier than this will often backfire as the mistime will lock you in place for the momentary recovery between dodges.

Coral cannon laser

The Sea Spider will fire a massive laser that sweeps across the arena. You’ve got two options here. If you’re close enough to the boss, the shot will be unable to reach you. Alternatively, move along a trajectory as the shot powers, then quickly change direction, i.e. vertically up to strafing hard left. The laser will lock onto the first flight path and follow that arc. It’s sweep isn’t actually all that long or thorough, so you’ll easily be out of harm’s way.

Two-pronged melee slam.

The Spider will raise its front legs, wreathing them in coral, then slam them down on you for a deadly AOE attack. If you’re far enough away, get into the air fast. Be aware that because it raises its limbs overhead before the slam, you can be caught by the move if you don’t clear a large enough vertical space in time. The safer alternative is to boost or dodge directly under the Sea Spider as it closes in, which will land you safely from the attack.

Overcharged machinegun volleys

In second phase, the Sea Spider will periodically unleash larger and faster barrages of small arms fire. This is a death sentence if enough of it hits, as it stuns devastatingly fast. The only great solution is to try and keep your distance, which renders this attack ineffective.

Coral annihilation

In second phase, the Sea Spider will unleash a colossal laser shot from its underside cannon, resulting in a massive fireball explosion. The only safe solution here is to get yourself far away. There’s a long telegraph on it, so as long as you’re in the air, it’s not too hard to avoid.

Spinning charge

As a last ditch effort, the Sea Spider will charge you in the second phase. By this point, the fight may likely almost be yours. If you have pulse armour or repair kits to spare, use them here. Otherwise, try to keep energy in reserves to execute doges and boosts to clear its path.

Maintain a consistent damage stream

The Sea Spider maintains a constant state of aggression, which is part of what makes it so dangerous. Your best bet to alleviate some of this pressure and create opportunity is to focus on maintaining constant damage to stun it. With the right long-range weapons, this isn’t actually too difficult. Rocket launchers are a good shout – they’ve got a decent amount of ammunition, excellent range, high damage, and do immense poise damage. Because of the boss’ size, it’s also pretty easy to score consistent hits.

Use your repair kits strategically

Repair kits are a lifeline (literally) in boss battles. Consider how you’re using them when fighting the Sea Spider. Relatively, phase one doesn’t have the damage potential of phase two. A hit in the former can be serious, a hit in the latter can be a wipeout. Aim to conserve your kits until later into the run, and ideally refrain from using them until your health bar is in the red. If you can make it into the second phase with at least one repair kit, you stand a much better chance of enduring and clutching victory.

Best AC parts for fighting the Sea Spider

We’ve touched on it throughout this guide, but considering your build carefully is an important strategy for this battle. Here then is a breakdown of some specific parts we’d recommend, and why we’re recommending them as suggestions for your build.

• DF-BA-06 XUAN-GE Bazooka. This rocket launcher has good range, deals excellent poise damage for stuns, and has a fast reload relative to its size and power.
• DF-GA-08 HU-BEN Gatling Gun. Fast fire rate, a huge magazine and reliable poise and conventional damage under sustained fire from mid range make this an excellent support piece for staying on the offensive and preventing poise damage recovery.
• HI-32 BU-TT/A Pulse Blade. If you’re confident enough to close and regain distance safely when the enemy is stunned, this is your best melee option. Pulse blades deal exceptional stagger damage to vulnerable targets, and the two-hit combo of this model grants it the highest damage potential for the weapons of this class you’ll have unlocked prior to the Ocean Crossing.
• Vvc-703PM Plasma Missile Launcher. This launcher is small and compact, firing only three missiles, but its AOE damage effects, decent base damage and rapid reload speed make it a great supporting option for stacking on damage.
• VP-60LCS Laser Cannon. This heavy shoulder-mounted laser cannon deals excellent poise and conventional damage. It boasts high accuracy and a good rate of fire, too.
• KASUAR/44Z Head. This head may have poor health, but its light weight, fantastic attitude stability, and high system recovery make it a workhorse in combat.
• BD-011 MELANDER Core. This core isn’t very agile, but it’ll provide a major boost to total hit points while further improving attitude stability for enhanced flight.
• NACHTREIHER/46E Arms. This lightweight arms are strong enough to support a range of weapon choices, while light enough to maintain an aspect of agility.
• LG-011 MELANDER Legs. Like the Core, these legs provide additional health and aerial stability bonuses. Although they’re heavy, they can support a substantial load, granting more flexibility in your approach to AC construction.
• BST-G2/P04 Boosters. These boosters might be a heavier, more energy demanding model, but their performance at this stage in the game is difficult to match. They provide great thrust and upward thrust, as well as a very high Quick Button thrust – vital for dodging deadly attacks.
• FCS-G2/P05 FCS. Guidance systems are a matter of personal preference, but this system does provide adequate bonuses for all ranges, making it a versatile choice.
• VP-20D Generator. This heavy duty generator has a few downsides, but its high EN capacity is difficult to argue with. It’ll provide all the necessary power for this build to function, and help you maintain flight consistently.

What is the Sea Spider?

The IA-13 Sea Spider is a deadly rogue weapon type created by the Institute. ‘Cinder’ Clara describes the Institute as an organisation of mad scientists who were active and prolific on Rubicon before the Fires of Ibis. The Sea Spider is a weapon type of theirs, called a C-Weapon, designed to wreak havoc at the command of its masters. With the Institute long since destroyed in the Fires, the enigmatic, coral-powered machine seemingly roams the upper levels of Grid 086, until your fateful encounter with it. You’ll need to defeat the Sea Spider boss to complete the Ocean Crossing mission and finish Chapter 2.

That’s everything for our advice on how to beat the Sea Spider in Armored Core 6. If you’re still struggling, try testing out some different parts to see what works for you. Or hone your skills in the arena to better get comfortable with the controls for your mech.