Arknights: Endfield Main Story Walkthrough — Chapters, Bosses, and Pacing

Valley-IV is the opening region and Chapter 1 runs four processes deep here before the story moves on. The first process, The Broken Lands, is eight missions running from Break the Siege through to the process finale Fort Showdown, and it exists to teach you the combat and base-building loops at the same time — expect the game to gate new mechanics behind almost every mission rather than dumping them all in the prologue. The second process, The Turbid Heavens, is a short three-mission bridge running Paving the Way through Maintenance Progress that mostly deals with getting Valley-IV's infrastructure stable before the plot escalates.

• Fort Showdown unlocks immediately after finishing the prior mission chain and carries no level restriction, so you can walk in underleveled if you are stubborn — you will just feel it.
• This is where you meet the region's signature boss, covered in detail below, so it is worth having your gear and skills touched up before you start the mission rather than mid-fight.

Rhodagn is the close-quarters brawler that caps off The Broken Lands, and nearly every attack he throws telegraphs with a red danger zone — a smaller inner circle expanding outward — that is your actual dodge timer, not his animation. He opens every fight with a Jump Press: a leap into the air followed by a ground slam, and the correct read is to wait for the expanding circle and dodge right before impact rather than dodging early.

• His flamethrower sweeps in a wide arc when you strafe left or right, which is great for baiting a dodge but will roast any AI-controlled allies caught in the arc, so reposition your team before pulling it.
• Continuously dodging through the flamethrower stream avoids damage and rapidly recovers SP, so treat that attack as a resource opportunity rather than something to just survive.
• Ranged characters let you keep distance from his melee kit entirely, while characters with well-timed counter skills can punish his landing recovery for a big damage window.
• After he shifts forms partway through the fight, he telegraphs an ultimate by leaping to the arena center and summoning four protective walls while charging — duck behind one to no-sell the blast.

Process three, Path of Ascension, is the longest stretch of Chapter 1 at ten missions running from The Mission Continues through to its finale, Cradle of Ages, which unlocks immediately with no level gate once you clear the prior mission and throws Triaggelos at you as a genuine marathon fight. Process four, Smoking Embers, runs nine missions from Entering the Endgame through to the process finale Conference of the Four in the OMV Dijiang hub, and it is where the Chapter 1 arc resolves — the finale mission itself is story-only, but the mission a few steps before it, Undying Cinders, is where you actually fight the process boss, Marble Aggelomoirai.

• Clearing Cradle of Ages is also the story gate for Exploration Level 4, reported to unlock together with the following mission, Beyond the World's Expanse 1 — worth knowing if you are wondering why an exploration tier feels locked.
• Both Path of Ascension and Smoking Embers assume you have been keeping your Operator loadouts current rather than coasting on Chapter 1 opening gear.

Triaggelos runs three full phases and fully heals between each, so pace your resources rather than burning cooldowns on phase one. It opens by dropping a meteor that does not track your position — just keep moving and it whiffs. Phase one leans on charge attacks you can interrupt with a Final Strike, Battle Skill, or Combo Skill the moment its red warning circle appears. Phase two summons adds and turns Triaggelos invincible while they are alive, so kill the adds first or you are wasting damage. Phase three goes fully ranged and the boss turns invisible between casts — strike the faint silhouette or track incoming projectiles back to their source, and hitting it just before a cast completes cancels the move and chunks its stagger bar. Bring healing support; this is not a short fight.

Marble Aggelomoirai is immune to direct damage in phase one — you have to destroy its four Aggeloi appendages to build stagger and expose the core, and if you run out of stagger before finishing the core, it resets with two fresh appendages instead of four. Phase two turns it into an airborne six-armed humanoid that hits mostly from above with spear combos, shockwaves, and arrow rain; ranged characters who can keep their distance from the sweeping AoEs do best here. There are no mid-fight checkpoints — dying restarts the whole encounter, so go in geared up.

Wuling opens Chapter 2 and currently runs six processes: Lost in the Marsh (3 missions), The Way of Water (5), The Long Feud (9), Tales of Old (5), Wrothful Tide (3), and Ponderous Load (4). The region's tone shifts noticeably from Valley-IV — Wuling's central conflict is a decade-old grudge between Wuling City and the displaced Stockade people, seeded by a Blight incident and a transport robbery that got most of the Stockade's men killed by Wuling's defenses. That backstory pays off directly in The Long Feud process, where the region's signature boss fight takes place. Tales of Old is the newest process, added with the version that opened the Marker Stone area, so if your game feels like it stops cold after Wuling's early processes, that is the current content wall rather than a bug.

Ruan Yi is Wuling's story boss and the emotional payoff of the Long Feud process — his father died leading the Stockade robbery, and Tangtang's adoption into Ruan Yi's family is part of what makes this fight land narratively as well as mechanically. The story version is reported around level 65, but bringing your team closer to level 80 gives real breathing room rather than a scrape-by clear.

• Phase one: Ruan Yi drops three Xiranite orbs you need to collect to break his invulnerable state — do not ignore them chasing damage, they are the actual objective.
• His slam attacks throw out shockwaves with real range; a ranged character sidesteps the problem entirely instead of dancing around melee.
• He heals to half HP at the start of phase two and comes back harder, summoning corrupted branches that need purifying with more collected Xiranite before you can resume damaging him.
• Watch for his counterable skill windows in both phases — landing burst damage in that window is worth more than a full combo thrown at a random moment.
• Two team archetypes are reported to work well: a physical build that stacks Vulnerable and then consumes it for a burst window, and a Solidification build that chains skills into a timed ultimate on the phase-two break.

Use this as a checklist before you walk into any of these fights — knowing the gimmick in advance turns every one of these from a wipe into a clean clear.

Outside the story line, Valley-IV also has open-world elite encounters worth flagging — the Axe Armorbeast, an armored horned beast that rams gates and enrages into large area attacks, shows up both roaming the map and as the priority target in the Area Defense: Valley Pass Level 3 challenge, where killing it early with concentrated tower fire prevents it from buffing every other enemy on the field.

Clearing the full main story up through the current content wall — all of Valley-IV and Wuling through Ponderous Load — is reported to run somewhere around 50 to 60 hours if you play every main mission, sit through mandatory tutorials, and do not skip cutscenes. That number does not include factory building, Operator leveling, or Authority Level grinding, so treat it as a floor, not a ceiling.

The recurring question is how much AIC factory and exploration work to do between missions. The honest answer: story unlocks access, side content buys efficiency. Most major systems — factories, sub-bases, upgrades, regional development — are gated behind Authority Level, and Authority Level is tied directly to story progress, so stalling on side content early just slows the story down later. That said, do not blow through every mission blind either — side missions that unlock a new mechanic, shop, or repeatable reward mode are worth doing the moment they appear, since they compound. A workable loop once you clear each process: push the next story beat until it gates on something, explore the newly opened map area, wire up power and Xiranite production (prioritize the Fluid Pump and a working power loop before anything fancier), upgrade recycling stations and trading posts to level 2-3, then go back to the story. Repeat that loop per region rather than trying to fully complete Valley-IV's side content before ever setting foot in Wuling — you will out-level the early side rewards long before you finish them.