THE BUILD

Mods
[Combat Discipline] is used to activate Arcane Avenger, could be rank 1 if you don't use an umbra forma. [Smoke Shadow] is used to boost critical chance, and [Seeking Shuriken] allows you to deal with particularly tanky enemies. Rolling guard is used to deal with AOE and cleanse DOT statuses.

Stats

• Duration: Good to invest into, as high invisibility uptime helps both survivability and damage
• Efficiency: Kept above 100, as Ash has a very low energy pool, though besides roar nothing he has costs too much energy
• Range: Nothing in this build relies on range since bladestorm is subsumed and teleport is still somewhat useful with only 20 meters of range
• Strength: Only purpose of going above 144% is to maximize roar boost

Arcanes
Arcane Avenger along with [Smoke Shadow] allows for high critical chance boosting, and Molt Augmented gives you bonus roar damage.

Helminth
Use roar as eclipse is so inconsistent that it's night unusable, and xata's whisper can be swapped in if you're using smite/bane/cleanse mods.

Archon Shards
Shard choice is pretty flexible, though recommend 1 blue health regeneration shard to help keep your healthy passively topped off. Extra duration, strength, energy orb effectiveness, and max energy are also very useful.

Other Equipment
Use a weapon that has high crit chance, and can apply a lot of slash, such as the [Acceltra] or [Kuva Chakkhurr]. [Adarza Kavat] can also be used to further boost your critical chance with [Cat's Eye] but isn't necessary. Magus Elevate can also be used for health sustain.

Playstyle
Keep roar and smoke screen up as often as you can, strip armor with the shuriken, and shoot shit.