Choir of One — Volatile Choir (Void Hunter)

Centerpiece: Choir of One (Auto Rifle · Special · Void) · Subclass: Nightstalker (Void) · Role: Invis-loop ad-clear that turns one Void gun into the whole Volatile engine Sandbox: 9.7.0 · Updated 2026-07-03

A Special-ammo Void auto rifle that hits like a primary: pour a radiolarian spread into the pack, aim down sights to body majors, and let the kills paint Volatile across the whole room. Gyrfalcon's bolts more Volatile onto the gun the instant you leave invisibility — and on Nightstalker you leave invis constantly. The gun makes the detonations, the detonations make the kills, the kills make the invis, the invis re-arms the gun. One Void weapon runs the entire loop.

The weapon

Command Frame (intrinsic): Fires extended-range, heavy-caliber projectiles at a reduced rate of fire. Deals increased precision damage when aiming down sights.

Fanatical Lance (exotic perk): Rapid final blows cause targets to explode into a pool of radiolarian fluid.

Choir of One Catalyst: (the catalyst's display string is blank in our manifest dump — `catalysts.md` line 28 has no description). The inferred payload is a Destabilizing-Rounds-style Void trait — closest sourced text, Destabilizing Rounds (`perks.md` line 761): Defeating a target creates a Void burst; hitting other targets with this burst makes them volatile and grants you Volatile Rounds for a short duration.

What it does in the hand: this is a Void Special-ammo auto rifle firing at 225 RPM. Two behaviours off one trigger — aim down sights for tight, heavy-caliber rounds that get Command Frame's precision bonus, so it bodies majors like a heavy primary; hip-fire for a slower radiolarian spread that detonates on impact, a shotgun-grade panic button up close. Fanatical Lance makes rapid final blows burst enemies into pools of radiolarian fluid, and the catalyst layers a Volatile-on-kill trait on top — so clearing a pack seeds elemental detonations that spread and kill more. Because it eats Special ammo, it sits in the energy slot where a fusion or shotgun would, freeing the kinetic slot for a real primary.

Loadout

Slot	Pick	Why
Subclass	Nightstalker (Void)	The invis engine that re-arms Gyrfalcon's Volatile Rounds every cycle.
Super	Shadowshot: Deadfall	Tethers the pack and weakens it, giving the gun debuffed targets to mulch and feeding Echo of Harvest's weakened-kill payoff.
Class ability	Gambler's Dodge	Dodge near enemies for a big melee refund; pairs with Vanishing Step to enter invis on demand and re-trigger Gyrfalcon.
Movement	Triple Jump	Three-stage aerial control to reposition between detonation clusters and line up ADS precision shots.
Melee	Snare Bomb (Quickfall)	Smoke bomb applies weaken and grants invisibility — another Gyrfalcon re-arm and a Stylish trigger.
Grenade	Vortex Grenade	Lingering AoE that (with Undermining) weakens and racks up the multikills that fuel Volatile.
Aspect 1	Stylish Executioner	Any elemental-debuffed kill grants invisibility and Truesight; Volatile is an elemental debuff, so the gun's own detonations trigger this with no cooldown.
Aspect 2	Vanishing Step	Dodging makes you invisible (+2 aspect energy); the deliberate "emerge from invis" button that re-arms Gyrfalcon whenever Stylish hasn't already fired.
Fragments	Undermining · Instability · Harvest · Starvation	Make Volatile self-sustaining and convert it into Weaken, orbs, breaches and Devour healing.
Exotic armour	Gyrfalcon's Hauberk (Chest)	Volatile Rounds on emerging from invis, plus a finisher-in-invis all-weapon damage buff and reserve overshield for the team.
Weapons	Kinetic primary (Voltshot/Hatchling/etc.) + boss-DPS heavy (LMG/rocket/GL)	Choir eats the Special slot, so keep a real primary for sustained trash; heavy covers the bosses and champions Choir can't stun.

Why it works (the mechanics)

• Two independent Volatile sources keep it always on. The catalyst's Destabilizing-style trait makes kills spread Volatile, while Gyrfalcon's See Me, Feel Me grants Volatile Rounds every time you emerge from invisibility (Clarity: 9 s of Volatile Rounds per exit). You leave invis constantly — Stylish on every debuffed kill, Vanishing Step on every dodge — so the gun is dripping Volatile between catalyst procs and topped back to full-uptime Volatile Rounds the instant you re-appear.
• Volatile is the keystone debuff, and the gun applies it to itself. A Volatile detonation counts as "any elemental debuff," which is exactly what Stylish Executioner consumes. So: shoot pack → Volatile detonations kill → Stylish → invis + Truesight → emerge → Gyrfalcon re-arms Volatile → shoot pack. The loop closes on the weapon alone; abilities are accelerants, not prerequisites.
• A Special-ammo Void primary-killer is the niche. Command Frame's ADS precision bonus lets it body majors like a heavy primary, while the hip-fire radiolarian spread is a point-blank deletion tool. Because it draws Special ammo it sits in the energy slot and frees the kinetic slot for a true primary — you carry two ad-clear guns, and Choir is the one that feeds the subclass.
• The fragment package converts Volatile into the whole Void economy. Echo of Instability (grenade kills grant Volatile Rounds) is a third Volatile source for when invis is spent; Echo of Undermining (Void grenades weaken) plus Deadfall's tether stack Weaken under the Volatile for a team-wide debuff; Echo of Harvest turns every weakened kill into an Orb of Power + Void Breach; Echo of Starvation turns that pickup into Devour. Shoot Void → Volatile + Weaken → kills → orbs and breaches → Devour heal → keep shooting.
• Gyrfalcon's finisher burst is the boss/champion window. Finish a target while invisible and all weapons gain a 35% damage buff for 6 s (Clarity) plus a reserve overshield for you and nearby allies, deployable on class ability. Truesight from Stylish makes finishing a weakened major trivial — that is your team-wide damage steroid right before a DPS phase.
• Deadfall is the reset button and the debuff battery. When a room overwhelms the loop, the tether pins and weakens the whole pack, hands the fireteam a shared debuff, and re-seeds the Volatile/Harvest chain from scratch — turning a stall back into a clean cascade.

Stats & mods

Weapons 200 → Class → Health. Weapons is the obvious primary — it is a weapon build, and the 9.7.0 stat adds PvE weapon damage on top of Volatile and Weaken. Class feeds Gambler's Dodge and Vanishing Step uptime (more invis = more Gyrfalcon re-arms); Health is the DR floor under Devour and Gyrfalcon's reserve overshield. Lean into the Weapons/Class armour archetype; push Super if you rely on Deadfall as the team debuff.

Fragment stat deltas (from `fragments.md`): Undermining −10 Grenade, Instability +10 Melee, Harvest neutral, Starvation −10 Class — net cheap and mostly Melee-positive.

Mods:

• Boots: Void Weapon Surge ×2 (surge damage on Choir) · Innervation/Insulation for ability energy on orb pickup.
• Arms: Special Ammo Finder / Special Ammo Scavenger so the Special-ammo gun never starves.
• Chest: Void/Arc/Solar Resist under the overshield and Devour layers.
• Class item: Powerful Attraction / Reaper to vacuum the orb flood Harvest and Siphon produce.
• Surge: Void Weapon Surge (matches Choir's element).
• Anti-Champion: none intrinsic — cover it with the artifact's Overload Grenades and a champion-stunning heavy (see below).

Artifact — NPA Repulsion Regulator

The all-Void artifact for an all-Void build: it pours the Void Breach loop full and reads the gun's element directly. Choir's Weaken/Volatile kills feed Breaches, the Breaches feed overshield and a weakening pulse, and an Auto Rifle node keeps the Special gun fed — plus the Overload stun the gun itself can't provide.

Picks (2/3/2):

• Tier 1: Unto the Breach · Volatile Flow
• Tier 2: Protective Breach · Overload Grenades · Targeting Autoloader
• Tier 3: Supernova · Void Weapon Channeling

• Unto the Breach creates a Void Breach whenever you defeat a Void-debuffed target — the loop's primary feeder, and Choir keeps everything Weakened and Volatile.
• Volatile Flow grants Volatile Rounds on Orb of Power pickup — a fourth Volatile source riding the orb flood that Harvest and Siphon mods generate.
• Protective Breach gives or refreshes an overshield on Void Breach pickup, stacking under Gyrfalcon's reserve overshield for a thick survivability layer.
• Overload Grenades makes your Vortex Grenade stun Overload Champions — the exact champion coverage this build otherwise lacks.
• Targeting Autoloader reloads and buffs your equipped weapon on kills while an Auto Rifle is equipped, keeping the Special gun firing between reloads.
• Supernova turns a Void Breach pickup into a next-shot weakening pulse, re-applying Weaken across the pack with Choir's own fire.
• Void Weapon Channeling grants a temporary Void weapon-damage bonus on Void kills while a Void ability is charged — near-permanent on Choir and a direct gun-damage payoff.

Where it shines

• Endgame ad-clear (GMs, −30/−40, Master content): Volatile chains plus Weaken thin packs while invisibility, Devour and the Gyrfalcon overshield carry survivability through multiple DR and heal layers. This is the build's home.
• Team play: Deadfall's weaken and Gyrfalcon's all-weapon damage burst plus fireteam reserve overshield make it a debuff/buff battery, not just personal clear.
• Champion coverage — flag it. Choir of One has no intrinsic champion stun (`weapon_facts.json` `champion: null`), and its non-standard auto frame is not covered by Anti-Champion 2.0 archetype rules. Treat the gun as carrying no stun: break Overload with the artifact's Overload Grenades (Vortex), pin and weaken elites with Deadfall's tether, and bring a champion-stunning heavy for Barrier/Unstoppable. Do not enter a GM expecting the gun itself to stun.

Mod selection (masterworked — full allocation)

All 15 sockets used, 10 energy per masterworked piece; costs from the manifest. Core mods are the build's engine; fill mods are strong defaults — swap freely (chest resists should match the activity's damage types). Flex/loadout-dependent: a champion-stunning heavy (see below).