Armored Core VI: Fires of Rubicon: Complete Guide

This guide covers the stagger system, assembly and parts stats, starter and boss-killing builds, the Arena and OS Tuning, the three endings across NG+ and NG++, and 100% completion tips for Armored Core VI.

Researched September 2026 — current as of the May 29, 2025 balance patch (the last gameplay update; it followed App Ver. 80 / Regulation Ver. 1.08.1 from May 21, 2025). A Dec 16, 2025 update touched only pre-order bonuses and the artbook/soundtrack app. Live games change; check the linked sources if something differs.

Quick Start

• Stagger is everything. Every enemy has an ACS (Attitude Control System) gauge. Filling it staggers them, and staggered targets take heavily boosted damage. Build to fill the gauge quickly, then hit hard during the stagger window.
• Checkpoint retries are free. You can restart from checkpoints and change your build between checkpoint attempts. When you die on a boss, you can re-enter the Assembly screen from the retry menu.
• Rebuild for the problem. The game expects you to change builds for bosses. There's no penalty for selling or buying parts: parts sell for their full purchase price.
• Always carry a burst weapon for stagger windows. Shotguns, pile bunkers, laser blades, grenade launchers, and charged weapons deal the big hits.
• Use your Repair Kits. You get a small number per mission (shown in the HUD). Don't die with kits left over.
• Do the Arena as it unlocks. Arena wins give OS Tuning chips, which unlock abilities like Weapon Bay and extra core expansions, plus permanent stat boosts.
• Scan often. The scan button shows items, enemies, and hidden part containers.
• Ignore lock-on range at first. Watch weight and EN load. Overweight legs make you slow and EN overload stops you from sortieing.

Controls Worth Knowing

Action | What it does

Quick Boost | Short, fast dodge in any direction; costs EN

Assault Boost | Long-range fast charge; good for closing distance and some mobility, burns EN

Hover / Boost | Hold jump to rise, boost to glide

Hard Lock | Keeps the camera locked on a target; helps with fast bosses

Scan | Pings nearby enemies, items, and data logs

Repair Kit | Restores AP

Weapon Bay (OS Tuning) | Swap back weapons into your hands

Boost Kick | A kick performed out of Assault Boost that builds stagger (the Controls screen shows the input)

Core Expansion | Assault Armor, Pulse Armor, Pulse Protection, or Terminal Armor

Assembly and Stats

Frame and inner parts

Slot | Why it matters

Head | Scan, some stability, AP

Core | Generator output adjustment, booster efficiency, AP

Arms | Arm load limit (how heavy your hand weapons can be), melee specialization, recoil control, firearm specialization

Legs | Load limit, AP, Attitude Stability, movement style (bipedal, reverse joint, tetrapod, tank)

Booster | Thrust, Quick Boost speed, EN cost

FCS | Lock-on speed at close, medium, and long range; missile lock correction

Generator | EN capacity, supply recovery, post-recovery EN supply

Expansion | One emergency tool (see above)

Key numbers to watch

• AP: health.
• Attitude Stability: how much impact you can absorb before being staggered. Heavier legs and cores raise it.
• Weight vs Load Limit: going over the load limit hurts movement badly.
• Arm Load: hand weapons can't exceed it without penalties.
• EN Load vs EN Output: if total EN Load exceeds your generator's output, you can't sortie.
• Impact and Accumulative Impact: how much a weapon fills the enemy ACS gauge.
• Direct Hit Adjustment: the bonus multiplier when you hit a staggered target. High values (shotguns, blades, pile bunker) make ideal stagger punishers.

Leg types

Legs | Strengths | Weaknesses

Bipedal | Balanced, flexible; good for learning | Nothing exceptional

Reverse Joint | Very high jumps, good aerial mobility | Lower stability than tanks

Tetrapod | Hover in the air; great for aerial shooting builds | Heavy-ish, weaker ground movement

Tank | Huge load and stability; wide weapon options | Slow turning, no normal jumps

Weapon Categories

Category | Role | Example parts

Rifles and machine guns | Steady damage and impact buildup | MG-014 LUDLOW, LR-037 HARRIS

Shotguns | Massive close-range impact and direct-hit punish | SG-027 ZIMMERMAN

Burst machine gun (energy) | Fast damage at close-mid range | MA-E-210 ETSUJIN

Melee | Enormous stagger punishes | Pile bunker PB-033M ASHMEAD, laser blades like Vvc-770LB (Laser Dagger) and IB-C03W2: MOONLIGHT

Grenade launchers and cannons | Explosive impact from range | DIZZY, SONGBIRDS (back unit)

Missiles | Lock-on chip damage and pressure | BML-G1/P20MLT-04, BML-G2/P03MLT-06, 45-091 JVLN BETA

Pulse and coral | Shield-stripping pulse, experimental coral weapons | Pulse blade, IB-C03W1: WLT 011 coral rifle

Stun | Stun needle launcher builds impact and briefly stuns | VE-60SNA

Recent balance (May 2025): MG-014 LUDLOW got faster projectiles and less weight and recoil. The ETSUJIN burst machine gun had its attack power and direct-hit adjustment reduced. DIZZY, the 44-141 JVLN ALPHA detonating bazooka, and the WS-5000 APERITIF siege missiles reload faster. The WLT 011 coral rifle's normal shots got stronger. The VP-61PS pulse shield now blocks less during its initial guard, and the VE-60SNA stun needle launcher got more attack power and projectile speed. If an older guide calls a part "the best", check it against these changes.

Starter and Boss-Killing Builds

"Stagger punisher" bipedal (general purpose)

• Hands: two shotguns (ZIMMERMAN is the classic) or one shotgun plus a laser blade.
• Back: SONGBIRDS grenade cannons (stagger from range) or dual missiles for tracking damage.
• Legs: medium bipedal with good Attitude Stability.
• Expansion: Assault Armor (an escape tool that also staggers).
• Plan: fill the gauge with missiles and shotguns, then hit the stagger with a melee or point-blank shotgun blast.

Tank "brick"

• Tank legs let you carry heavy back weapons such as grenade cannons alongside rifles or shotguns.
• Very forgiving for players who struggle with dodging.
• Best against bosses that throw lots of small, fast attacks. Weaker when you need to dodge big sweeping beams.

Aerial tetrapod

• Tetrapod legs plus missiles and rifles. You hover above ground-bound enemies and chip them down.
• Strong against grounded bosses. Weaker against bosses with good anti-air.

Bosses — Key Tips

Boss | Where | Tip

AH12: HC Helicopter | Tutorial | Missiles and rifles. Keep moving and use Quick Boost when it fires volleys

HA-T-102 Juggernaut | Chapter 1 | Its front is heavily armored. Quick Boost past its charge and shoot the back. Stagger opens it up

AAP07: BALTEUS | Chapter 1 finale | The first skill check. Break its Pulse Armor with pulse or high-impact weapons, stay mid-range, and Quick Boost sideways through missile walls. Shotguns plus SONGBIRDS or dual missiles is a classic answer

EC-0804 Smart Cleaner | Chapter 2 | Stay behind it and out of the molten spray. Heavy weapons punish its staggers

C-Weapon SEA SPIDER | Chapter 2 | Handle its leg phase, then its aerial phase. Missiles work well when it flies

IA-02: ICE WORM | Chapter 3 | Scripted fight: follow the mission's instructions to break its shields with the provided tools, then hit it hard during openings

NIGHTFALL / Raven | Chapter 3 | Duel against a very aggressive AC. High stability and burst weapons

General boss rules:

• Circle strafe and Quick Boost at the right moment. Many big attacks are dodged by boosting sideways at the last moment, not away.
• Watch the enemy's ACS bar. When it's nearly full, get ready to punish. Save your melee or pile bunker for that window.
• Change builds after each death if the plan clearly isn't working.

Arena and OS Tuning

• The Arena (the combat simulator) unlocks early and new ranks open as the story progresses.
• Each win gives OS Tuning chips. Spend them in OS Tuning on:
• Weapon Bay: lets back slots use hand weapons, for example four shotguns.
• Core expansion options: unlocks Pulse Armor, Pulse Protection, and Terminal Armor.
• Stat upgrades: damage bonuses by weapon type, stagger-related improvements, repair kit options.
• OS Tuning can be reset for free, so experiment.

Story Routes and Endings

The game has three endings across multiple playthroughs:

Ending | How to reach it

Fires of Raven | Side with Handler Walter's plan at the final branch

Liberator of Rubicon | Side with Ayre at the final branch

Alea Iacta Est | Only available in NG++, which unlocks new missions and a different final path involving ALLMIND

• NG+ keeps your parts and adds new missions and branch choices. Several missions play out differently.
• NG++ is needed for the third ending and some remaining parts.
• You can play missions from any chapter again through Replay Mission, which is how you pick up missed parts and S-ranks without starting over.

Collectibles and Completion

• Hidden parts containers: scan in every mission. Many parts only come from containers or combat logs.
• Combat logs: collect them by destroying named ACs and MTs. Completing a pilot's full set of logs rewards you with parts.
• S-ranks: each mission is graded on your performance (clear speed and how much damage you took matter most). S-ranks give extra rewards, and S-ranking every mission is its own achievement (The Perfect Mercenary).
• Achievements: all three endings (The Fires of Raven, Liberator of Rubicon, Alea Iacta Est), every parts collector (weapons, internal, external, expansions), Combat Log Collector, Master of Arena, Tuning Expert (fully tuned OS), and The Perfect Mercenary (all S-ranks).

Common Mistakes to Avoid

• Keeping one build for every mission. The game is built around rebuilding.
• Staying at range without a stagger plan. Chip damage alone makes bosses long and dangerous.
• Boosting away from big attacks instead of sideways.
• Running out of EN. Watch the EN bar. If EN runs dry, you can't Quick Boost.
• Forgetting about Assault Armor. It staggers attackers and clears missiles.
• Skipping the Arena. OS Tuning upgrades make everything easier.
• Ignoring weight and arm load warnings. Overloaded ACs feel terrible.

Advanced Tips

• Boost kick into a stagger for extra impact. A kick cancel can start punishes early.
• Pair two hard-hitting weapons with different reload timings so you always have something ready when a stagger triggers.
• Stun needle and charged weapons hit hardest against targets that are already staggered.
• Watch the Direct Hit Adjustment stat. A weapon with high raw damage but low direct-hit value is worse at punishing staggers than it looks.
• PvP (1v1 and 3v3, Ranked): online needs the latest update and regulation. Ranked seasons reset rank and leaderboards periodically, and the top players get Name Plates.
• Decal and paint are purely cosmetic, but AC files can be shared with your community.

FAQ

How long is the story? A first playthrough is roughly 20–30 hours. All three endings need NG+ and NG++, which are shorter because you keep your parts.

Is there a difficulty setting? No. You adjust difficulty by changing your build.

How do I beat Balteus? Use high-impact or pulse weapons to break the Pulse Armor, then shotguns, missiles, and grenades to build stagger, and a close-range punish during stagger. Quick Boost sideways through missile barrages.

Do I keep parts after NG+? Yes. Parts, money, and OS Tuning carry over.

What changed in the latest patch? The May 29, 2025 patch buffed the LUDLOW, DIZZY, JVLN ALPHA, WLT 011 coral rifle, APERITIF, and stun needle launcher, nerfed the ETSUJIN, and toned down the VP-61PS pulse shield, along with other adjustments.

Is Armored Core VI still getting updates? No gameplay changes since May 2025. The Dec 2025 update only affected the extra apps.

Sources

• Armored Core VI on Steam (store page and announcements)
• Official announcement: Update distribution notice (May 29, 2025)
• Official announcement: Update distribution notice, App Ver. 80 / Regulation 1.08.1 (May 21, 2025)
• Official announcement: Release Note for 2025/12/16
• Fextralife Armored Core 6 Wiki: Bosses
• Steam achievements list
• Wikipedia: Armored Core VI: Fires of Rubicon