Ergo Sum — Gathering Light (Hunter)
Weapon: Ergo Sum (Sword · Heavy · Strand/elemental) · Subclass: Prismatic · Role: Transcendence battery + melee/sword bruiser Sandbox: 9.7.0 · Created 2026-06-16
The only sword built to be put away. Final blows stack Gathering Light; stowing dumps the whole stack into melee, grenade, and class energy at once — a manual Transcendence pump. The catalyst closes the loop the other way: Transcendent-grenade damage refunds sword ammo. So you swing to charge, stow to ability-spam, go Transcendent, throw the grenade that makes more sword, and swing again. It's a Prismatic Hunter that fights with its abilities and reloads them with its Heavy.
The weapon
Final blows with this weapon grant stacks of Gathering Light, improving guard stats and lunge range. Stowing this weapon consumes all stacks, granting melee, grenade, and class ability energy.
Catalyst — Transcendent Steel: Dealing damage with a Transcendent grenade grants Ergo Sum ammo.
Read those two together and the playstyle writes itself. The intrinsic is two weapons in one: held, it's a swinging melee weapon whose guard and lunge grow as you kill (Gathering Light is the same buff Traveler's Chosen uses); stowed, the accumulated stacks become a burst of melee + grenade + class energy. The more you kill before you holster, the bigger the ability dump. The catalyst then gives you ammo back specifically for spending Transcendence — which on Prismatic you build by using both Light and Dark abilities, the exact abilities Ergo Sum just paid for. Nothing else in the game ties a Heavy weapon this tightly to the Prismatic Transcendence economy.
Loadout
| Slot | Pick | Why |
|---|---|---|
| Subclass |  Prismatic Hunter | The only kit with Transcendent grenades — the catalyst is dead on any other subclass. |
| Super |  Silence and Squall (Stasis) | Storm + freeze; pairs with Winter's Shroud and feeds the Dark side of the Transcendence bar. (Storm's Edge if you'd rather a roaming melee Super.) |
| Class ability |  Gambler's Dodge | Melee energy on dodge (scaled by Melee stat) — a second melee charge on top of the stow-dump. |
| Melee |  Combination Blow (Arc) | Kill → heal + escalating melee damage + full melee refund. The on-foot kill engine that isn't the sword, so the sword's stacks survive the holster. |
| Grenade | Threadling / Grapple | Grapple to close on packs and make Tangles; Threadling for ad-pressure. The Transcendent version is what the catalyst rewards — throw it into a pack for the ammo refund. |
| Aspect 1 |  Stylish Executioner | Any elemental-debuffed kill → invis + Truesight; next melee while invis weakens. Free safety between stow-dumps. |
| Aspect 2 |  Winter's Shroud | Dodging slows nearby targets — slow is a Stasis (Darkness) debuff that lights Stylish and feeds Transcendence; pairs with Gambler's melee refund. |
Facet of Balance Light kills → melee, Dark kills → grenade — both halves of the stow-dump get topped further
Facet of Honor Elemental pickups / Tangle destruction → Transcendence — Grapple Tangles feed this
Facet of Blessing melee final blows → health regen — Combination Blow is constant healing
Facet of Bravery powered-melee kills → Unraveling Strand rounds; a Strand Ergo Sum eats that
Facet of Generosity Transcendent kills → ally orbs
Exotic armour — Star-Eater Scales (Leg Armor): Feast of Light — Orbs of Power overcharge a full Super for a healing burst, bonus Super damage, and an overshield at max. This build is an orb fountain (Combination Blow + Transcendent kills + finishers), so Star-Eater keeps Silence and Squall always charged and overcharged. Every stow-dump and Transcendent throw also builds toward the next Super, and Star-Eater turns those frequent Supers into both DPS and a survival button. (Alt: Gifted Conviction for jolt-DR if you swap to an Arc Super.)
Other two weapon slots:
- Kinetic Primary — a Strand or Stasis Primary so Facet of Bravery / Winter's Shroud debuffs feed Stylish; any Overload/Barrier frame for champion coverage (Ergo Sum carries no champion stun — see below).
- Special — a Solar or Void Special (Special Finisher mod fed by orbs) to hold champions and bosses while Gathering Light recharges. A Strand/Stasis Glaive or shotgun also keeps the debuff theme.
Why this works (the mechanics)
- Stowing is the build, not a footnote. Gathering Light pays you for killing then holstering. Stack 5–10 kills, swap to the Primary, and the dump refills melee + grenade + class in one swap. The optimal habit is to swing the sword into a pack, holster mid-fight, and spend the abilities it just bought.
- The catalyst makes the Heavy self-feeding. Transcendent-grenade damage → sword ammo. On Prismatic you reach Transcendence by alternating Light and Dark abilities — which the stow-dump just refunded — so the grenade that crests the bar also restocks the weapon that built it. The loop never asks a Heavy brick.
- Combination Blow keeps the sword's stacks alive. Killing on foot with the Arc melee (and healing off it via Facet of Blessing) means you don't have to spend Ergo Sum to keep fighting — so its Gathering Light stacks ride until you choose to cash them, maximising the dump size.
- Two debuff sources light Stylish for free. Winter's Shroud slow (dodge) and Facet of Bravery / a Stasis-Strand Primary mean almost every kill is on a debuffed target → invis + Truesight between dumps. Safety is automatic, not a cooldown you babysit.
- Everything converges on Transcendence and orbs. Facet of Balance tops both ability halves, Facet of Honor turns Grapple Tangles and Stasis/Strand pickups into Transcendence, Facet of Generosity floods orbs while Transcendent — and Star-Eater turns that orb flood into an overcharged Super on demand. One kill loop powers melee, grenade, Super, and the sword's ammo simultaneously.
Stats & mods
Melee 200 → Super 100+ → Class. Melee 200 maxes Combination Blow / Gambler's refund and the melee half of every stow-dump; Super feeds Star-Eater's overcharge cadence; Class for dodge uptime (Winter's Shroud + Stylish trigger). Grenade rides as the secondary dump target. Health is the dump stat — Combination Blow heals, Facet of Blessing heals, Star-Eater overshields, Stylish goes invis.
Archetypes: Brawler / Specialist pieces (Melee-Super-Class favoured). Mods: Sword Scavenger + Sword Ammo wherever possible (keep the Heavy fed alongside the catalyst), Heavy Handed / Melee Wellmaker, 
Bomber (class energy on grenade), Special/Heavy Finisher for orb generation → Star-Eater fuel, and a surge matching your Ergo Sum element on boots. Stat-tune +Melee/−Health.
Where it shines
- Add-dense PvE — Onslaught, Nightfalls, Legend/Master content. The swing → stow → ability-dump → Transcendent grenade → ammo-refund loop wants packs, and it generates its own orbs/Super/heal so it sustains indefinitely.
- Mini-boss / orange-bar clear. A fully-stacked Gathering Light sword with max guard and lunge deletes majors; Combination Blow's escalating damage stacks on top for the ones you punch instead.
- Champion coverage — flag. Ergo Sum carries no intrinsic champion stun (swords aren't an Anti-Champion 2.0 archetype, and the perk grants no bespoke stun). Bring champion stuns on your Primary/Special: Barrier/Overload frames as the content demands. Winter's Shroud slow and Stylish weaken help control champions but do not stun them — the guns do the stunning.
Mod selection (masterworked — full allocation)
| Piece | Mod · cost | What it does |
|---|---|---|
| Helmet (5/10) | Strand Siphon 1e fill | Rapid Strand weapon final blows create Orbs of Power. |
| Hands-On 3e fill | Gain bonus Super energy on melee kills. | |
| Heavy Ammo Finder 1e fill | Increases the effect of all contributions towards the Heavy ammo meter. | |
| Arms (6/10) | Heavy Handed 3e | Your powered melee final blows create Orbs of Power. |
| Melee Kickstart 1e fill | When your melee energy is fully expended, your Armor Charge is consumed and you gain melee energy for each Armor Charge used. | |
| Momentum Transfer 2e fill | Causing damage with a grenade reduces your melee cooldown. | |
| Chest (6/10) | Strand Resistance 2e fill | Reduces incoming Strand damage from combatants. |
| Concussive Dampener 3e fill | Reduces incoming area-of-effect damage from combatants. | |
| Sniper Damage Resistance 1e fill | Reduces incoming damage from combatants that are at long range. | |
| Legs (9/10) | Strand Scavenger 3e | Strand weapons get bonus reserves when picking up ammo used by that weapon. |
| Strand Weapon Surge 3e | Your Strand weapons gain a small bonus to damage while you have any Armor Charge. Your Armor Charge now decays over time. | |
| Strand Weapon Surge 3e fill | Your Strand weapons gain a small bonus to damage while you have any Armor Charge. Your Armor Charge now decays over time. | |
| Class Item (3/10) | Bomber 1e | Reduces grenade cooldown when using your class ability. |
| Reaper 1e fill | Shortly after using your class ability, your next weapon final blow spawns an Orb of Power. | |
| Outreach 1e fill | Reduces melee cooldown when using your class ability. |
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: **Special/Heavy Finisher** for orb generation → Star-Eater fuel.