Wonton's video: MAGE TOWER Artifact Challenge - Assassination Rogue - Guide in Description

IMPORTANT: USE LEECHING POISON TO SUSTAIN. Prydaz is not required. It only does 30k HPS, while Leeching Poison can do 100k+ if you have good damage. Standard single-target talent setup, multi-dot as much as possible since the bosses share health. There are 3 mobs, which share health. Sigryn has to reach 20% for the fight to end. Basic mechanics: Jarl Velbrand melees you for a little bit, and throws spinning axes that deal about 500k Runeseer Faljar casts Shadowbolts for about 100k, and puts some fel pools on the ground that tick for about 400k every 0.5 seconds if you stand in them. Sigryn occasionally does a knockback ability on you. Golden yellow orbs periodically drop in the arena. I think these heal, but I didn't really need to use them. 3 shadowy runes periodically spawn. They shrink in size over time, and when they shrink to zero, they explode for about 3 million damage. Running over the runes makes them disappear without taking any damage. As an Assassination Rogue, I got a buff that reduced Blind's cooldown to 30 seconds (and its duration to 35 seconds). Empower: Sigryn periodically empowers one of the enemies (she can empower herself). Empowered Jarl gains a BIG damage buff (500% or so) but reduced movement speed. KITE HIM, or pop Evasion and facetank. Empowered Runeseer gains a 5M absorb shield, and starts a 20-second cast that, once completed, performs a massive AoE nuke that will probably 1-shot you. The cast is uninterruptible while the shield holds. Either break the shield and interrupt him, or just use an immunity right before the cast completes. Empowered Sigryn continuously pulses massive unavoidable damage for 20 seconds. This is where I used Blind, which stopped her from doing the damage. Later mechanics: Starting at about 1 min into the fight (maybe % based? couldn't tell), walls of Dark Val'kyr appear and, after a few seconds, rush across the arena, dealing lethal damage. Find the gap in the wall and stand in it. Jarl performs a Bladestorm ability that slowly pulls you towards him. If you're in melee range, it deals about 900k Physical damage per second. Run against this to avoid being sucked into melee range. This is an attrition and execution fight. As far as I can tell, it has no soft or hard enrage, and Leeching Poison provides you with enough sustain if you know how to DPS. It is probably the most forgiving artifact challenge, having way less ilvl/Legendary requirements than any of the others, only having about a 700-800k DPS requirement (something that is definitely possible on 3 targets, even in Heroic NH gear). Good luck!