Coldheart — The Eternal Beam (Arc Hunter)

Centerpiece: Coldheart (Trace Rifle · Special · Arc) · Subclass: Arc (Arcstrider) · Role: Never-stop-firing sustained-DPS beam on majors, minibosses and bosses Sandbox: 9.7.0 · Updated 2026-07-03

Coldheart pays you for not letting go of the trigger — the laser ramps the longer it stays on one target, so peak damage is back-loaded onto the boss. The catalyst refills the mag while you're amplified; Cenotaph Mask reloads it for free and turns it into a fireteam Special/Heavy ammo printer. Stack those three and the beam quite literally never stops: Arc keeps you amplified, amplified keeps the mag full, the full mag keeps the beam alive. It's a loop with no off-switch.

The weapon

Cold Fusion (intrinsic, verbatim): "This weapon shoots a steady cold-fusion-powered Arc laser, dealing more damage the longer it remains on a target."

Coldheart Catalyst — Supercharged Magazine (verbatim): "While amplified, ammo is gradually transferred from reserves to the magazine. While in Speed Booster, ammo regenerates faster and overflows the magazine."

Coldheart is a continuous-beam Arc Trace Rifle whose per-tick damage escalates the longer the beam dwells on a single target — the meaningful number is back-loaded, so the worst thing you can do is stop firing or swap targets early. That single fact dictates the entire build: everything below exists to keep the beam on and the magazine full. The catalyst solves the magazine half — the mag refills from reserves whenever you're amplified, and overflows while in Speed Booster — so you reach the high end of the dwell curve instead of clipping it on a reload. The subclass keeps amplified lit, and the paired exotic removes the last scrap of downtime. Plant, hold, ramp; the beam is a held-trigger DPS wall.

Loadout

Slot	Pick	Why
Subclass	Arc (Arcstrider)	Amplified is the catalyst's trigger; jolt clears the trash the beam doesn't dwell on, and Arc kills feed the ability economy.
Super	Gathering Storm	Throw-and-forget Arc Staff — jolts and sticks a lingering damage zone so you keep beaming while it ticks.
Class ability	Marksman's Dodge	Reloads on dodge — a manual top-up of the beam on demand, and repositions without dropping fire for long.
Movement	Triple Jump	Air control to keep line-of-sight on the dwell target between beams.
Melee	Combination Blow	Melee final blows keep you amplified between gunfights — the cheapest way to stay in the catalyst's mag-refill window.
Grenade	Arcbolt Grenade	Chains to jolt multiple targets; jolted kills make Ionic Traces (Spark of Ions) and refund ability energy.
Aspect 1	Flow State	"Defeating a jolted target makes you amplified." The keystone — Arc kills keep amplified up, which keeps the catalyst's mag-refill running and speeds reloads.
Aspect 2	Lethal Current	"After dodging, your next melee attack has increased lunge range, jolts the target, and creates a damaging aftershock." Manufactures the jolted targets Flow State needs, off the dodge you already use to reload — and every jolted kill sprays Ionic Traces.
Fragments	Spark of Ions · Spark of Discharge · Spark of Amplitude · Spark of Beacons	Two Ionic-Trace sources feed the abilities, one makes Orbs while amplified, one blinds the pack off every Arc Special kill.
Exotic armour	Cenotaph Mask (Helmet)	Auto-reloads the Trace mid-fight and turns Coldheart into a fireteam ammo economy — removes the only downtime the catalyst can't.
Weapons	Anti-Champion Primary (Kinetic) + Arc Heavy	Primary covers the Barrier/Unstoppable stuns the subclass can't; an Arc Heavy shares Surge mods and burst the beam's ramp is too slow to deliver.

Why it works (the mechanics)

• The build is one closed loop with no entry cost. Be amplified → the catalyst transfers reserves into the mag mid-beam → you keep firing → Arc kills keep you amplified (Flow State on jolted kills, Combination Blow on melee kills). The thing that runs the loop is also the thing the loop produces; once it's lit, the beam doesn't stop.
• Cenotaph Mask removes the only remaining downtime. High Priority "steadily reloads a portion of your equipped Trace Rifle's magazine from reserves" — so even without amplified the mag tops itself up. The catalyst handles amplified uptime, Cenotaph handles the gaps: two independent auto-reload sources stacked on the one gun that punishes reloading.
• Cenotaph turns Coldheart into a fireteam ammo economy. Damaging a boss or Champion with the Trace marks it; when an ally defeats the marked target, you get Special ammo and your allies get Heavy. You tag the boss with the beam (which you're doing anyway) and become a self-sustaining Special battery feeding the squad's Heavy.
• Dwell damage rewards the boss phase this build is built to survive. The ramp is back-loaded, so the big number lands on whatever you hold the beam on longest — a miniboss or boss. Cenotaph plus the catalyst guarantee you never run the mag dry mid-ramp, so you actually reach the high end of the curve.
• Jolt and blind clear the adds the beam isn't dwelling on. Lethal Current and Arcbolt jolt; jolted kills chain and make Ionic Traces; Spark of Beacons blinds the pack on every amplified Coldheart kill. The single target you're ramping is the only thing you steer the beam onto — the trash dies to chains and blinds around it.
• Ionic Traces double-feed the abilities that feed the gun. Spark of Discharge (Coldheart kills) and Spark of Ions (jolted kills) both spray Ionic Traces; collecting them returns ability energy and tops amplified. The gun pays for the dodge and melee that keep the gun firing.

Stats & mods

Weapons 200 → Class → Health. Weapons is the only stat that scales Coldheart's PvE damage and its sustained-beam ramp; max it. Class keeps Marksman's Dodge — your on-demand reload — charged. Health is the dump. Archetype lean: a Weapons-primary Gunner set with a Class secondary.

Mods:

• Boots: Innervation (orb pickup → grenade energy) · Absolution to trim ability cooldowns.
• Arms: Heavy Handed (melee kills restore melee energy — Combination Blow uptime) · Melee Font.
• Chest: Arc Resistance ×2 + one other Resistance — flat DR while you stand still holding a beam, stationary and exposed by design.
• Class item: Powerful Attraction (dodge vacuums the Ionic-Trace orbs) · Bomber (dodge → grenade energy).
• Surge: Arc Weapon Surge ×2 on boots — straight onto Coldheart (surge is a manifest/tuning value; see Verify).
• Anti-Champion: none intrinsic on Coldheart — routed through subclass jolt (Overload) plus blind, and an anti-Champion Primary for Barrier/Unstoppable.

Artifact — Slayer Baron Apothecary Satchel

The Arc-leaning Satchel pool plugs straight into Coldheart's jolt → blind → Ionic-Trace loop and pays off the Armor Charge / Orb economy the dodge already generates; Champions stay covered by subclass jolt (Overload) plus the blind these mods amplify.

Picks (2/3/2):

• Tier 1: Trace Evidence · The Thick Of It
• Tier 2: Retinal Burn · Curative Orbs · Debilitating Wave
• Tier 3: Arc Compounding · Conductive Cosmic Crystal

• Trace Evidence makes Ionic Traces from rapid precision hits or final blows on jolted or blinded targets — exactly Coldheart's kills — and picking the Trace up grants an Armor Charge.
• The Thick Of It grants Armor Charge on rapid final blows while surrounded — fuel for Retinal Burn, plus handling while you hold the beam.
• Retinal Burn spends an Armor Charge on rapid Arc precision hits for a blind burst — Coldheart is a precision Arc beam, so it free-stacks Spark of Beacons' blind.
• Curative Orbs makes an Orb of Power on shield break — feeds Spark of Amplitude and the dodge's Powerful Attraction vacuum.
• Debilitating Wave gives an Arc finisher wave — a panic clear that matches Gathering Storm's theme.
• Arc Compounding makes Arc sources deal more damage to blinded targets — your beam ramps harder on the packs you blinded.
• Conductive Cosmic Crystal buffs your Arc (and Void) ability damage against Stasis-debuffed targets — a legal T3 pick but idle here (this kit runs no Stasis source); see Verify.

Where it shines

• Sustained-DPS boss/miniboss damage: the dwell ramp plus guaranteed mag uptime is a held-trigger DPS wall — ideal for any encounter where you can plant and beam (Nightfall bosses, dungeon minibosses, raid majors).
• Fireteam content: Cenotaph's mark → ally-kill → Special-for-you / Heavy-for-them is a team utility; the build peaks in a 3-stack where you're the ammo printer.
• Champion coverage: Coldheart breaks nothing intrinsically — Trace Rifles carry no Anti-Champion 2.0 stun and Cold Fusion has no bespoke stun text. You cover Overload via subclass jolt (Arcbolt / Lethal Current / jolted chains) and stagger everything, Champions included, via blind (Spark of Beacons / Retinal Burn). Bring an anti-Champion Primary for a hard Barrier/Unstoppable wall.

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: stationary; an anti-Champion Primary for Barrier/Unstoppable.