I made this simply to transfer the Circuit Stalker's build, minus the glaring inefficiencies.This will one shot pretty much anything that can have a finisher done to it, and assuming you use Marked for Nerf instead of something like [Savage Silence] or [Radiant Finish], it will potentially kill everything around you too. Obviously this is meant for situations where kills per second isn't as important as single target damage, for example Rathuum/Index or an assassination mission. I recommend using a zaw so you can also make use of Exodia Might for free healing. Ultimatum can proc from [Fatal Teleport] or bladestorm finisher kills.

For those wondering how it compares to Stalker:
Effective health of this build: 1275 × (1675/300) + 375 = 7494
Effective health of Stalker: 1110 × (563/300) + 555 = 2638*

Smoke screen - this build: 18.8s, 35 energy
Smoke screen - Stalker: 18s, 75 energy

Fatal Teleport - this build: 74.4m, 558% extra damage
Fatal Teleport - Stalker: 87m, 346.25% extra damage

Stalker gets +300% crit chance against enemies that can't see him. [Ash] gets slash procs that are 25% stronger and last 50% longer.

Personally I believe bladestorm is significantly stronger than Punishment. It costs 12 energy per enemy (6 while invisible, and refunds the cost if the enemy dies before all 3 marks are spent so it ends up being free most of the time), deals 3580 damage per finisher (10740 per enemy) with forced bleed (156693 = 42282 total bleed damage per enemy, grand total of 53022 damage per enemy that ignores armor for 6 energy) and allows you to continue killing elsewhere unhindered. Punishment costs 100 energy, multiplies enemy damage gained by 7.5x for ~3 seconds, and then shoots out projectiles in a wave in front of him that do not home and have no punch through. It costs more, only the slash dots ignore armor, it cannot trigger arcane ultimatum, and anyone that has used [Nyx]'s absorb knows that multiplying enemy damage is pitifully weak, no matter how high the multiplier is.

*Stalker also has [Adaptation], but the whole point of his kit is to be invisible, so unless you run out of energy (you won't because [Ash]'s kit is incredibly energy efficient, and stalker has passive energy [Regen] and arcane energize), or intentionally don't make yourself invisible (bad idea since he relies on that heavily), then stray hits won't do enough to give you real benefit from that. IF you had max stacks for every damage type hitting you active at the same time, then EHP for stalker is 20831. That's a best case scenario.