As we know, in Season 4 ranged rogue builds with either Victimize or Precision are very dominant. Subsequently, melee builds, DoT builds and trap builds fell behind considerably. You still can play them, but you won’t be as powerful and efficient as the aforementiones ranged builds.
Now, DoT builds are currently in a weird spot. They used to be really strong, but their strength, unfortunately, stemmed from bugs and unintended interactions. Hence, they were fixed at some point and left untouched since then. And when compared to the buffed Precision and Victimize builds, DoTs are MILES behind.
Blizzard representatives told us more then once that they want to see a build variety and don’t want to take away ‘power fantasy’ from players. So, in my opinion, if they want to keep their words, they should reconsider some of the poison-related skills and aspects.
The one thing that they can do it, is to let Rogue take a leaf out of Barbarian’s book.
Now bear with me.
Currently, Barbarians have the strongest DoT setup in the entire game. There are many factors for this, including double-dipping, good damage multipliers and some interesting interactions. But the main thing that catches my eye is this:
Rupture
Skewer enemies in front of you, dealing X damage, then rip your weapon out, damaging enemies for their total Bleeding amount and removing all Bleeding damage from them.
The so called ‘reaping’ effect is obviously very strong for DoT builds, and it may be that one puzzle piece that will complete Poison rogue and make it relevant in the current meta.
Here’s my take on some ways to implement this mechanic to the rogue kit by adding some new aspects and/or changing old ones:
#1
Damaging Vulnerable enemies with an Agility skill deals [60%-120%] of their total Poisoning amount as Poison damage and removes all Poisoning damage from them. 10s cooldown.
This should be self-explanatory. You stack a lot of “greyed health” and then reap that damage with an agility skill. Vulnerable condition for more control over reaping.
#2
Poison Trap no longer applies poisoning. Instead it damages enemies for [60%-120%] of their total Poisoning amount and removes all Poisoning damage from them.
Same as the previous one. This would make Poison trap (or maybe any other trap or grenade skill) into a nuke.
#3
Critical strikes with Core skills now deal [5-10%] of the enemy’s Poisoning amount as Poison damage once per cast.
This, on the other hand, is not a nuke, but a consistent damage modifier. The more poison is stacked, the more additional damage you do. “Once per cast”, because otherwise multihit core skills like Rapid fire would do excessive amounts of single-target damage.
#4a
Toxic alchemist’s aspect
Lucky Hit: Damaging enemies infected by Shadow Imbuement with Poison Imbued skills has up to a 75% chance to create a toxic explosion that deals[x]Poisoning damage over 5 seconds to the target and surrounding enemies. If the enemy was already Poisoned, it deals [10%-20%] of their total Poisoning amount as Poison damage an removes [10%-20%] of Poisoning damage from them.
I feel like “alchemist” aspects in general are wasted for being flat damage. This way these aspects would find their use. Also, there’s Icy and Poison alchemist. But where’s shadow? Here’s my take:
#4b
Shadow alchemist’s aspect
Lucky Hit: Poison Imbued skills has up to a 15% chance to apply Shadow Imbuement. If the enemy was already infected with Shadow imbuement, it erupts, dealing [10%-20%] of their total Poisoning amount as Shadow damage to the target and surrounding enemies and removing [10%-20%] of Poisoning damage from them.
It should be noted that the reaping damage, especially AoE, should not have any lucky hit chance, otherwise it would be able to trigger Victimize and that would be a bit excessive.
There’s also a way to implement reaping to a key passive. We have at least one passive that is not used anyway 
Cutthroat and Marksman Core skills deal 5%
[x]of the total Poisoning amount inflicted to the enemy as bonus damage once per cast.This damage is further increased by 100%
[x]of your Cutthroat Damage bonus or Marksman Damage bonus, depending on the skill used.
Not sure how to fit Core damage into that description. Maybe it should be gone altogether and removed from older uniques and paragon nodes, like it was removed from affixes.
Why such a big multiplier (100%)? Well, there’s only so much Cutthroat and Marksman damage sources in the game. Excluding Core damage nodes, you’ll have 700% of it, tops. And don’t forget that withough CQC key passive poison builds deal approximately 50% less damage.
You might say ‘Such a mechanic would be broken’.
Well, lest you forget, some classes are dishing out billions of damage, oneshotting ubers and world bosses. Moreover, Bleed Barbarians are using this mechanic since Season 2 and they have much better multipliers. Now rogues are not the strongest class in the game atm, not even with Victimize and Precision buffs. But hopefully, Blizzard will change it and even the playing field.
TL;DR: Giving ‘Reaping’ mechanic (same as Barbarian’s Rupture) to Poison Rogues might be a way to save them from oblivion.