Osteo Striga — Plague Weaver (Kinetic Hunter)

Centerpiece: Osteo Striga (Submachine Gun · Primary · Kinetic) · Subclass: Strand (Threadrunner) · Role: Infinite-ammo poison add-clear + Tangle/Threadling chain engine Sandbox: 9.7.0 · Updated 2026-07-03

Osteo isn't a damage gun, it's a crowd liquefier. Tag one target, the corruption burst leaps to its neighbours, they rot and die, the catalyst refunds the mag, and the gun never stops. The whole build turns that endless stream of poison kills into Tangles, Threadlings and Woven Mail, so the same held trigger that clears the room also keeps you alive and keeps your abilities full. Strand is the thematic and mechanical home: poison spreads, Strand spreads, and both feed each other off one trigger.

The weapon

Screaming Swarm (intrinsic): "Fires a stream of sentient, toxic projectiles that track the targeted enemy."

Toxic Overload (catalyst-enabled trait): "Landing a final blow or multiple precision hits triggers a burst that inflicts nearby targets with potent corruption."

Osteo Striga Catalyst: "Final blows with corruption return ammo to the magazine."

What it does: the projectiles soft-track, so accuracy is a non-issue — you point in the general direction and let the swarm find heads. A final blow or stacked precision hits detonates a corruption burst that poisons everything nearby; those poisoned targets die over time, each death counts as a corruption final blow, and the catalyst refunds rounds to the mag. In a dense pack the loop is self-sustaining: one kill seeds poison, the poison kills three more, those refund ammo, the mag never empties. It is one of the best add-clear primaries in the game for sheer throughput, and it does it from cover at any range thanks to the tracking. It is a Kinetic primary, so it pairs with Strand by theme and ability economy rather than by matching surge.

Loadout

Slot	Pick	Why
Subclass	Strand — Threadrunner (Hunter)	Poison-spread and Strand-spread overlap; Osteo kills become the Tangle/Threadling/Orb economy.
Super	Silkstrike	Roaming Strand Super for surge windows; the whip suspends and clears when Osteo can't keep pace.
Class ability	Marksman's Dodge	Instant Osteo reload plus reposition between poison bursts; covers the rare mag drain in a thin crowd.
Movement	Triple Jump	Air control to reach dive angles and reposition over a pack.
Melee	Threaded Spike	Ranged boomerang that suspends and severs, and returns Threadlings on the way back.
Grenade	Grapple	Repositions and, with Widow's Silk, drops a Grapple Tangle — free Whirling Maelstrom fuel and Cyrtarachne Woven Mail.
Aspect 1	Widow's Silk	Extra grenade charge and your Grappling Hook creates a Grapple Tangle — turns grapple into a Tangle dispenser.
Aspect 2	Whirling Maelstrom	Destroying a Tangle weaves a Strand mass that seeks targets and emits Unraveling projectiles on kills — chains alongside the poison.
Fragments	Thread of Generation · Thread of Ascent · Thread of Warding · Thread of Transmutation	Close the loop: damage feeds grenade, grenade reloads, orbs re-arm Woven Mail, and weapon kills under Woven Mail print Tangles.
Exotic armour	Cyrtarachne's Facade (Helmet)	Grapple grants Woven Mail on demand; while active every kill restores health and flinch resistance holds the swarm's lock through incoming fire.
Weapons	Osteo Striga (Kinetic primary) + a Special stun-frame + a Strand/Heavy DPS piece	Osteo clears; the other two slots carry single-target punch and the champion stuns Osteo lacks.

Why it works (the mechanics)

• One trigger feeds two spread systems. Osteo's corruption burst leaps target-to-target while Whirling Maelstrom's Strand mass seeks target-to-target. You manufacture a pack-wide chain reaction from a single held trigger, and the two systems clear at different ranges so nothing escapes.
• The mag is functionally infinite in a crowd. The catalyst refunds ammo on corruption final blows, and poison kills are corruption final blows, so a dense room tops the mag faster than you drain it. Marksman's Dodge covers the rare reload when the crowd thins.
• Corruption kills are the whole ability economy. With Woven Mail up from Grapple, Thread of Transmutation turns every Osteo final blow into a Tangle; destroy it and Whirling Maelstrom weaves. Thread of Generation turns the constant damage into grenade energy for another Grapple, another Tangle and fresh Woven Mail. The loop is closed — kills make Tangles make grenade makes Woven Mail makes more kills count.
• Cyrtarachne converts add-clear into sustain. Woven Mail damage resistance plus health on every kill while it's active plus flinch resistance means the poison stream is also your healing source. You can facetank packs that would delete a normal primary build.
• Orbs close the survivability gap. Poison kills flood Orbs through a Kinetic Siphon mod, and Thread of Warding re-applies Woven Mail on pickup, so Woven Mail effectively never drops even between Grapples.
• Honest scope: an add-clear chassis, not a DPS or champion answer. Osteo is a Kinetic primary with no intrinsic champion stun, so champion duty is offloaded to the subclass suspend and the other two weapon slots. Osteo's job is to guarantee there is never a wall of adds between you and the champion.

Stats & mods

Weapons 200 → Class → Health. Weapons for universal PvE damage on the primary that does all the work; Class high for Marksman's Dodge uptime (reload plus the Woven Mail re-trigger cadence); Health as the floor since Woven Mail and kill-heal already cover survivability. The archetype lean is a Weapons/Class piece — Grenade is welcome for more Grapples but Thread of Generation and Thread of Ascent feed it for free.

Mods:

• Boots: Kinetic Weapon Surge ×2 (17% Osteo damage — straight onto the gun doing 90% of the work) · Orbs of Restoration.
• Arms: Heavy Handed / melee energy on melee kills (Threaded Spike loop) · Grenade Font if pushing Grapple uptime.
• Chest: Elemental resist mods (Solar/Arc/Void) layered under Woven Mail.
• Class item: Powerful Attraction (Dodge vacuums orbs into Thread of Warding to re-arm Woven Mail) · Bomber/Outreach for ability uptime.
• Surge: Kinetic Weapon Surge — Osteo is Kinetic, so Strand surge does nothing for it; match the gun, not the subclass.
• Anti-Champion: none intrinsic — sourced from Strand suspend/sever and the seasonal artifact anti-champion mods (see below).

Artifact — Tablet of Ruin

The Strand-flavoured artifact for a Strand Threadrunner: it amplifies the exact Tangle → Unravel → Sever chain Osteo manufactures, turns the orb firehose into Unraveling Rounds on the gun itself, and offloads champions to suspend/sever rather than the Kinetic SMG (which stuns nothing).

Picks (2/3/2):

• Tier 1: Unraveling Orbs · Elemental Siphon
• Tier 2: Vile Weave · Horde Shuttle · Flashover
• Tier 3: To Shreds · Elemental Supercharger

• Unraveling Orbs arms Osteo with Unraveling Rounds every time you scoop an Orb or Tangle — free anti-barrier spread bolted onto the add-clear stream.
• Elemental Siphon makes Kinetic rapid final blows print elemental pickups, doubling the orb economy Thread of Warding feeds on.
• Vile Weave makes your Grapple and Whirling Tangles sever and refund their own cooldown, seeding the sever loop the rest of the artifact pays off.
• Horde Shuttle spawns severing Threadlings when you damage unravelled targets, stacking onto Maelstrom's chain.
• Flashover is the best remaining on-theme pick; the rest of the tier is Void/Glaive/Trace-locked.
• To Shreds unravels severed targets under sustained fire and drops a Strand hotspot on the kill, closing the sever → unravel loop Osteo drives.
• Elemental Supercharger feeds Silkstrike energy off defeating severed targets, paying back all the Sever the build applies.

Where it shines

• Add-dense PvE: GM Nightfalls, Legend/Master Lost Sectors, Onslaught, dungeon and raid trash rooms — anywhere a tide of minors and majors needs to evaporate. Osteo plus Maelstrom turn a horde into a self-clearing chain.
• Survivability content: the Woven-Mail-kill-heal loop lets you hold ground in −20/−30 rooms that punish a squishy primary build.
• Champion coverage: Osteo stuns nothing intrinsically (Kinetic SMG, no bespoke stun perk). Bring the stuns from Strand suspend (Threaded Spike, Silkstrike) plus the Tablet of Ruin anti-champion mods and your Special/Heavy slots — a stun-frame Special for Barrier/Unstoppable and a Machine Gun or Rocket for Overload and boss DPS.

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: not the subclass. - **Anti-Champion:** none intrinsic — sourced from Strand suspend/sever; the seasonal artifact anti-champion mods (see below).