Armored Core VI: Fires of Rubicon: Complete Walkthrough & Boss Guide
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🗺️ Main Story Walkthrough
Tick off each step as you go — your progress saves locally, no account needed.
You begin as the mercenary pilot C4-621, codenamed Raven, landing on the industrial planet Rubicon 3 in a high-risk illegal entry drop. The first missions familiarize you with Armored Core VI's core combat rhythm: boost aggressively toward enemies, use the Assault Boost to close distance, and learn to read the orange stagger meter above every enemy which, when filled, opens a guaranteed high-damage window. The chapter culminates in the “Attack the Watchpoint” mission and the Balteus boss fight. Equip dual Songbird grenade launchers on your shoulders and dual Buerzel assault rifles on your arms before attempting Balteus — this loadout stacks impact fast enough to reliably trigger ACS Overload on his shield.
Chapter 2 opens the full scope of Rubicon's three-faction conflict: Arquebus Corporation, Balam Industries, and the Rubicon Liberation Front (RLF). Missions include sabotaging corporate infrastructure, escorting RLF units through combat zones, and your first encounters with enemy AC pilots in the Arena. The “Destroy the Ice Worm” mission introduces large-scale multi-target encounters where you must use Assault Boost charge attacks to deal damage during the Ice Worm's brief vulnerability windows. Arena fights in Chapter 2 are good currency earners — defeating every available Arena opponent before the chapter ends funds better leg parts that improve ground stability in the Sea Spider fight ahead.
Chapter 3 is when AC6 introduces Decision Missions — branching choices that alter which missions you complete and ultimately determine your ending path. The major decision here involves whether to support or oppose the RLF's independence movement. Regardless of your choice, Chapter 3 ends with the “Reach the Coral Convergence” mission arc and the IB-C03 HAL 826 / Ibis series boss encounter. Ibis is the game's mechanical difficulty spike; equip dual Zimmerman shotguns with Songbird grenade launcher shoulders and practice Quick Boost canceling between attacks. Ibis punishes hovering — stay mobile on the ground between burst windows.
Chapter 4 escalates the corporate war with missions targeting Arquebus's flagship weapon platforms and Balam's fortified excavation sites. You face V.IV Rusty as an ally in one mission and as a potential opponent depending on your route — fighting alongside Rusty is one of the game's most enjoyable co-pilot sequences. The “Intercept the Corporate Forces” mission features the V.I Freud AC fight, who uses a high-impact pulse weapon that can stagger your AC in two hits; equip a Pulse Armor generator for this fight. Coral extraction missions in this chapter yield materials for leg and generator upgrades that significantly extend your Assault Boost charge time.
The final chapter converges all faction storylines around Rubicon's Coral — the energy resource central to the game's conflict and Ayre, the Coral intelligence who has guided Raven throughout. A second major Decision Mission appears here, splitting the final mission sequence into three distinct ending paths: “Liberator of Rubicon,” “Fires of Raven,” and “Alea Iacta Est.” Each ending requires a different final mission chain and boss. Complete the game once to unlock New Game Plus, which adds a third playthrough path and reveals additional story context about ALLMIND and Ayre's true nature. The true final boss (ALLMIND) is only accessible in the third playthrough.
Armored Core VI requires three full playthroughs to unlock all endings and the complete story. Your parts inventory, OST Chips, and OS Tuning upgrades carry over between runs. New Game Plus introduces new missions, additional Arena opponents, and revised versions of several Chapter 3–5 missions with altered enemy compositions. The “Alea Iacta Est” ending path is exclusive to your second playthrough while the true ending featuring ALLMIND as the final antagonist requires your third. Prioritize acquiring the IB-C03 W2: WLT 101 laser turret shoulder weapon in NG+ — it is the most efficient tool for the ALLMIND fight's first phase.
⚔️ Boss Guides
AAP07: Balteus
Attack Patterns
Balteus is the Chapter 1 final boss and the game's first true skill check. He is encased in a regenerating pulse shield that blocks most damage until depleted. His primary attacks include a barrage of heat-seeking missiles that fire in large spreads, a flamethrower sweep used at close range, and a massive electric pulse that simultaneously regenerates his shield and deals area damage. At 50% health he activates Assault Armor, an AoE explosion triggered after a brief charge-up; Ayre provides an audio warning when this is imminent.
Strategy
The dual Zimmerman shotguns rapidly chip the pulse shield through impact damage — stay within 80 meters and alternate fire to maintain consistent pressure. Once the shield breaks, switch to Songbird shoulder launchers for burst damage directly to the hull during the stagger window; a full Songbird volley into a staggered Balteus removes roughly 35% of his HP. In phase two, when his Assault Armor primes, boost vertically upward and away the moment Ayre warns you — the blast radius is large but does not track upward quickly. Repeat shield-break cycles after each Assault Armor use. Avoid circling horizontally only; vertical movement makes his missile spreads significantly easier to dodge.
IA-13: Sea Spider
Attack Patterns
The Sea Spider is a massive arthropod boss fought mid-game in a large open arena. In phase one it is grounded and attacks with crushing foreleg slams, a charged plasma cannon from its front-mounted turret, and mine deployments around the arena perimeter. Its front cannon has a slow but devastating lock-on beam in addition to the standard burst fire. In phase two it lifts off and transforms the cannon into an orbital laser that tracks across the full arena floor, firing in sustained sweeps rather than single shots.
Strategy
Phase one weakness: position directly underneath the Sea Spider's central body. This position is nearly immune to all foreleg attacks and sits outside the front cannon's minimum angle — only the rear mine deployer can hit you here. Fire Zimmerman shotguns upward at the undercarriage to build stagger; two stagger cycles end phase one. When it lifts off for phase two, ascend to maximum altitude using Assault Boost and attack the head-mounted sensor array. The orbital laser always begins its sweep from the arena's left edge — start each dodge cycle by boosting right, and re-engage during the laser's reset animation. Tetrapod legs are strongly recommended for the aerial phase as they provide the hovering stability needed to maintain aim on the head while airborne.
V.II Snail
Attack Patterns
V.II Snail is an Arquebus Vespers AC encountered in Chapter 4, notable for his Coral energy shield that regenerates faster than Balteus's pulse shield. He fights at medium range using a high-accuracy laser rifle, coral-infused homing missiles, and a coral explosion burst deployed at close range. His defining trait is exceptional defensive play — he Quick Boosts more aggressively than any previous AC pilot and is rarely stationary, making sustained damage difficult.
Strategy
Energy weapons bypass a portion of his coral shield's regeneration rate; equip plasma rifles or dual laser rifles for consistent shield pressure. Unlike Balteus, aggressive closing is counterproductive — Snail's close-range coral burst punishes flanking attempts. Instead, maintain 150–200 meter engagement distance and fire continuously to prevent full shield regeneration between your shots. When his missile volley locks on, Quick Boost directly toward him rather than perpendicular — missiles lose tracking at close angles. Save Songbird shoulder charges for the post-stagger window; a double Songbird volley into a staggered Snail at medium range is the fight's most efficient damage opportunity.
"Cinder" Carla (with Chatty Stick)
Attack Patterns
The “Eliminate Cinder Carla” mission is a simultaneous two-AC fight in an open arena with minimal cover. Chatty Stick is the aggressive melee-ranged attacker who closes distance rapidly with Assault Boost charges and uses a pile driver weapon. Carla fights from range with charged energy cannon blasts and acts as the suppressive fire element of the duo. Both ACs target you simultaneously and there is very little natural cover in the arena to separate them.
Strategy
Ascend immediately at mission start to draw both ACs' attention upward, then quick-boost toward Chatty Stick specifically and unleash both Zimmerman barrels at close range. He has the lower stagger threshold of the two — two close-range double blasts will stagger him. Activate Pulse Armor the moment Carla begins charging her cannon while you focus on Chatty — the armor absorbs one full charged shot, maintaining your offensive momentum. Once Chatty is staggered and then eliminated, reposition to mid-range and engage Carla in a standard Zimmerman-shotgun/Songbird stagger cycle. Never let Carla land a charged cannon hit without Pulse Armor active as it will one-shot lighter builds.
IB-C03 HAL 826 / Ibis Series
Attack Patterns
The Ibis series boss is a coral-form entity protected by a constellation of drone satellites that orbit it and fire crisscrossing laser patterns. In its opening phase it charges forward at very high speed, using the drones as a kinetic battering ram. It flies over the arena firing a massive sustained charged beam and performs a dual-blade slash when Raven's AC is caught inside the drone formation. The drone lasers in formation create interlocking patterns that are nearly impossible to dodge by boosting through them laterally.
Strategy
The opening charge should be met with a melee blade counter — Quick Boost forward into the charge and immediately trigger the blade attack; this deals significant damage and passes through the drone formation in a single animation. For the aerial charged beam, boost perpendicular to Ibis's flight path rather than away from it, as the beam tracks forward velocity. When the drone laser formation activates, ground yourself and Quick Boost in short bursts rather than sustained flight — the lasers have minimal downward tracking and hovering makes you a stationary target. Use Songbird volleys during every stagger window; the dual Zimmerman close-range pressure is what consistently fills the stagger meter given Ibis's drone shield absorbs ranged fire from outside the formation.
Ayre / IB-01: CEL 240 (Ending Boss)
Attack Patterns
Ayre's transformed final form in the “Liberator of Rubicon” ending is a heartbreaking encounter against the Coral intelligence who guided Raven. She uses coral-infused energy blades at close range, homing coral spheres that detonate in clusters, and a massive coral beam channeled from the Coral convergence above. In phase two she generates a sustained coral aura that passively damages nearby ACs, forcing constant repositioning. Her attacks are fast but every major ability has a unique audio cue from her voice.
Strategy
Treat this fight identically to Balteus mechanically: use the dual Zimmerman close approach to strip her coral barrier through impact damage, then Songbird volleys into the stagger window. The coral sphere clusters can be outrun by Assault Boosting directly through the formation’s center gap rather than around the edges. In phase two, maintain 120–150 meter distance to minimize passive aura damage while still landing Zimmerman blasts at the edge of effective range. When she channels the coral beam, the audio cue gives you approximately 1.5 seconds to Quick Boost perpendicular — this is the fight's mechanical test and the timing is consistent across all three runs.