[Ash]'s take on stealth is to passively move between enemies while everyone around him drops to the floor. His 4th skill buffed by savage does enough damage to kill standard level-cap heavies in a single set of stabs.

Abilities explained:

Shuriken: Tosses 2 shurikens that force bleed procs. Due to lack of scaling it's not a great ability for damage.
Smoke Screen: An AOE stagger followed by relatively brief invisibility. Used in an emergency if trickery refuses to cooperate.
Teleport: Teleports you to the target, if it's an enemy opens them to a finisher. If used while your 4 is killing stuff, join the clones to help them stab the marked enemies.
Blade Storm: Press to start marking enemies, press again to unleash clones that will stab all marked enemies thrice.

Note: It might be tempting to use shuriken augment in order to strip enemies but due to ashe's 4th skill doing pure damage armour strip isn't necessary. While invisible (from any source of invisibility) marking enemies costs only half the price.

What skills to swap out for a subsume: Shuriken. Although you can stay invisible with trickery alone, 2's still good in a pinch and 3's decent for increasing clear speed leaving shuriken as your go-to swap skill. 3 also has niche uses spy vaults, mobility and helping your clones out makes you invulnerable for a bit acting as some survivability.

Core:

Savage silence is an 800+% boost to your 4ths hitting power so it's an auto-include.
Arcane [Fury] provides a massive increase to the damage done by your 4.
[Umbral Intensify] and [Blind Rage] give you more than enough raw stopping power to go around.

Alternatives: If you don't have Arcane [Fury] use [Steel Charge].

Quality of Life:

[Enemy Radar]: Stacks well with [Primed Animal Instinct] allowing you to plan your engagements and never be surprised about what's around the corner, even if said corner is 60 meters away. And let's face it, auras as a slot suck, hard.

Alternatives:

[Streamline]: You can run [Firewalker] instead of [Streamline]. The 4 elemental bullet jump mods increase your mobility the most out of all bullet jump mods and out of those [Firewalker] has the most useful forced proc.

Economy:

Most of your energy will be spent on casting your 4 while trying to have savage up.
Ashe's 4 got reworked to only cost 1/3rd of the energy it used to while still having its price halved if you cast it while invisible. This means maintaining a healthy economy is fairly trivial.
Keep duration at neutral or above without dumping range as well as some efficiency.
[Primed Flow] allows you to mark a full room of enemies in a single cast as well as give you breathing room against enemies and procs that can drain your energy.
Zenurik is nice to keep you topped, and if everything else fails, pop a pad.

Alternatives: If you're having issues with economy you can knock a few ranks off of [Blind Rage].

Survivability:

Arcane trickery procs when you kill something with your 4 (but not via slash procs). Luckily [Banshee]'s augment only boosts the damage your 4 does, not the slash damage over time, meaning that it's fairly unlikely to kill enemies with the proc itself making trickery very reliable even against enemies you won't kill in a single shot.
Shield gating and the shield reset with augur message make stray shots a non-issue as long as you're spending energy.
In a punch, you can still cast your 2/3 if needed.
[Primed Sure Footed] prevents you from being stunlocked and allows you to use explosive weapons with no issues.
[Banshee]'s silence will keep enemies around you stunlocked long enough for them to be marked and killed by your 4.
Spoiler Mod helps out with the healing and lockdown if needed.

Alternatives: If you don't have [Primed Sure Footed] go for [Vigilante Pursuit], [Speed Drift], Synth swap or [Handspring]. If you're struggleing with survivability, especially against the infested consider using slotting [Rolling Guard] on the build.

Subsumes:

Silence, the whole build revolves around the [Savage Silence] augment. Without it enemies die to slash procs from the stabs rather than the stabs themselves which does not trigger trickery.

Gameplay:

Before you start playing this build I'd advise you to mod your melee weapon like so. As well as to have a decent primer ready as reliably viral application quadrupoles your damage. Once you're done with the prep, do the following:
Build up your combo by meleeing the first few enemies you see then run between enemies with silence on, mark large crowds with 4 then press 4 again to watch the blood fireworks [Flow]. Periodically melee a few units for arcane [Fury] and use your primer to prime problematic targets so that they die in one stab rather than two or three.

Q&A:

Q0: Why is there no HP/armour/facetankmod#177013.
A0: Because DE doesn't know how to balance the game and shield gating+Spoiler is so strong anything with 1 shield doesn't need additional survivability that alone the fact that invisibility is just as broken yet they just don't care.

Q1: Why not [Rising Storm]?
A1: [Rising Storm] just helps you build combo, with enough attackspeed and range that's already done extremely fast. Mod your melee properly and that augment won't be useful for a 4-oriented DPS build.

Q2: I keep getting killed and....
A2: Git gud.