Osteo Striga — Plague Weaver (Hunter)

Weapon: Osteo Striga (Submachine Gun · Primary · Kinetic) · Subclass: Strand (Threadrunner) · Role: Infinite-ammo poison add-clear + Tangle/Threadling chain engine Sandbox: 9.7.0 · Created 2026-06-16

Osteo isn't a damage gun, it's a crowd liquefier. Tag one target, the poison burst leaps to its neighbours, they die, the catalyst refunds the mag, and the gun never stops. The whole build is built to turn that endless stream of corruption kills into Tangles, Threadlings and Woven Mail — so the same 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 held trigger.

The weapon

Screaming Swarm (exotic 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. Final blows (and stacked precision hits) detonate a corruption burst that poisons everything nearby; those poisoned targets die over time, each death is 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 the single best add-clear primary in the game for sheer throughput, and it does it from cover at any range thanks to the tracking.

Loadout

Slot	Pick	Why
Subclass	Strand — Threadrunner (Hunter)	Poison-spread + Strand-spread overlap; Osteo kills become the Tangle/Threadling/Orb economy.
Super	Silkstrike (or Shackle Grenade-heavy Spectre setup)	Roaming Strand Super for surges; suspends and clears when Osteo can't keep pace.
Class ability	Marksman's Dodge	Instant Osteo reload + reposition between poison bursts; full-mag uptime.
Movement	Triple Jump	Air control to reach Ensnaring Slam dive angles over a pack.
Melee	Threaded Spike (Threadling-on-return)	Ranged boomerang that suspends/severs; bonus Threadlings off your own engine.
Grenade	Grapple	Spends a grenade charge to reposition AND (with Widow's Silk) drops a Grapple Tangle = free Whirling Maelstrom fuel + Cyrtarachne Woven Mail.
Aspect 1	Widow's Silk	Extra grenade charge + your Grapple 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.

Exotic — Cyrtarachne's Facade (Helmet)

Acrobat's Focus: "Activating Grapple grants Woven Mail. While active, Woven Mail provides flinch resistance and health when defeating targets."

This is the keystone. Grapple (you have a spare charge from Widow's Silk) gives Woven Mail on demand, and while it's up every kill restores health — and Osteo kills come in floods. So the gun that clears the room is also the gun that heals you, and the flinch resistance lets you hold the trigger through incoming fire without the swarm losing its lock. It also gates Thread of Warding and Thread of Transmutation: Woven Mail up → orbs re-arm it → final blows mint Tangles → Maelstrom. Cyrtarachne is what makes Osteo a survivable primary instead of a glass one.

Why this works (the mechanics)

• One trigger feeds two spread systems. Osteo's corruption burst leaps target-to-target; 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. Catalyst: corruption final blows refund ammo. 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.
• Corruption kills are the whole ability economy. With Woven Mail up (Grapple → Cyrtarachne), Thread of Transmutation turns every Osteo final blow into a Tangle → destroy it → Whirling Maelstrom. Thread of Generation turns the constant damage into grenade energy → another Grapple → another Tangle + 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 (~30%-ish DR) + "health on every kill while it's active" + flinch resistance means the poison stream is your healing source. You facetank packs that would delete a normal primary build.
• Orbs close the survivability gap. Poison kills flood orbs (Siphon mod); Thread of Warding re-applies Woven Mail on pickup, so Woven Mail effectively never drops even between Grapples.
• Honest scope: this is an add-clear chassis, not a DPS or champion answer. Osteo is a Kinetic primary with no intrinsic stun and no bespoke champion perk — it handles no champion type by itself. Champion duty is offloaded to the subclass (suspend) and the other two weapons (below). Osteo's job is to make sure there's never a wall of adds standing between you and the champion.

Stats & mods

Weapons → Class → Health. Weapons 100+ (universal PvE damage on the primary that does all the work), Class high for Marksman's Dodge uptime (reload + Woven Mail re-trigger cadence), Health as the floor since Woven Mail + kill-heal already cover survivability. Grenade is welcome (more Grapples) but Thread of Generation + Thread of Ascent feed it for free.

Mods (standard armour-mod pool):

• Helmet: Kinetic Siphon (poison kills → Orbs — this build's orb firehose) · Kinetic Targeting/Dexterity for handling.
• Gauntlets: Heavy Handed / melee energy on melee kills (Threaded Spike loop) · Grenade Font if pushing Grapple uptime.
• Chest: Resist mods (Solar/Arc/Void) under the Woven Mail layer.
• Boots: Kinetic Weapon Surge ×2 (≈+17% Osteo damage — straight onto the gun doing 90% of the work) · Orbs of Restoration.
• Class item: Powerful Attraction (Dodge vacuums orbs → Thread of Warding re-arms Woven Mail) · Bomber/Outreach for ability uptime.

Armour set bonus is garnish — any Strand- or Tangle-flavoured 2pc is fine; chase the stats first.

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 + 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 (the gap, stated plainly): Osteo stuns nothing intrinsically. Cover it with: - Strand suspend — Threaded Spike, Ensnaring Slam (if slotted over an aspect), and the seasonal artifact anti-champion mods (suspend/sever → Unstoppable/ Overload behaviour). Pull the exact champion mapping from the live 9.7.0 artifact. - Your other two slots carry the actual stun frames. Suggested pairings: - Special: a Strand or Solar weapon whose archetype stuns Barrier or Unstoppable (e.g. an Aggressive/High-Impact frame → Unstoppable) and adds the single-target punch Osteo lacks — a Fusion or Sniper. - Heavy: a Machine Gun or Rocket for bosses/Overload duty and the burst DPS this build otherwise has none of. A Strand Heavy also keeps the subclass surge consistent.