This build is a DPS focused [Vauban] build used mainly for endurance steel path missions e.g. Survival or Circuit. Bastille is used for crowd control and armor strip while Flechette Orbs from minelayer are used to do DPS that scales with enemy level (multiplied by 1+enemy level/10), at a faster rate than enemy HP scales. In addition, ability strength (2.83x), Vaubans passive (1.25x), overdriver (1.46x), [Vigorous Swap] (2.65x) and arcane arachne (2.5x) are all multiplicative damage buffs for [Flechette] orb. This means at level 101, each [Flechette] nail deals an average damage of around 200,000 damage while at level 9999, each nail does an average of 15 million damage, which increases to 90 million after 10 stacks of viral status (created by nourish). Keep in mind a fully armored corrupted heavy gunner at lvl 9999 has 18.7 million EHP (and 7.5 million HP), meaning flechette almost one-shots with zero viral status.
Alternative options are to use Arcane Avenger to increase [Flechette] orbs Crit chance to 95%, and [Tek Collateral] to boost the crit muliplier to 4x, but this will require you to run Combat Discipline, and possibly equilbrium with dispensary instead of spectrorage/spectrosiphon to both heal and get energy - see TwistedBolt's crit version: https://overframe.gg/build/270804/vauban/minmaxed-one-man-killing-zone/ . Also see booben's version which inspired this build: https://overframe.gg/build/417663/vauban-prime/boobens-flechette-dps-vauban/
UPDATE 2024
With armor cap changes, you no longer even need to Bastille to full strip enemies in order to one-shot levelcap enemies. This means you can clump enemies with vortex, allow your companion to passive prime with any combination of viral/corrosive/heat status and just let [Flechette] kill everything.
UPDATE 2023
Nourish applies Viral Damage to Flechettes AND gives an energy multiplier of 2.83x, meaning Energize gives 424 energy per trigger, energy orbs give 70 energy per orb and Archon Stretch generates 6 energy/s when Tesla Nervos is used.
Archon shards: Use two amber cast speed and three duration or strength shards
UPDATE Oct 2023
With shield gate changes, we now require Brief Respite and Augur Mods to regenerate sufficient shields for shield gating. With Brief Respite, Augur Reach and 1-2 augur mods on pistol, a cast of Bastille now generates 418 shields, which corresponds to approximately 1.5s shield gate.
Duration
Required for uptime on spectrorage, bastille and [Flechette]
Efficiency
Dumped due to [Blind Rage]. Make up for energy economy with [Primed Flow], Nourish, Achon [Stretch] and any other sources such as [Grimoire] [Xata Invocation], emergence dissipate, [Dethcube] [Energy Generator] etc
Range
Important for Bastille range, Tether coil grab range and nourish [Retribution] range and vortex range should you wish to collapse your bastilles
Strength
Important for Bastille enemy capacity, armor strip rate, [Flechette] damage and overdriver boost
Flexible Slots
[Augur Reach] and [Umbral Intensify] are flexible for [Vigorous Swap], [Augur Secrets], [Augur Message], [Tesla Bank] or Repelling Bastille
ExilusPSF is best in slot.
Flexible for handspring, cunning drift, power drift
ArcanesEnergize - sustaining energy with spectrorage and 45% efficiencyArachne - +150% damage boost to flechette orbs after wall latch
Avenger - flat +45% crit chance to the base 50% crit chance of [Flechette] orbs
Archon Shards2 cast speed shards
3 duration shards