Poison dmg and which class is best for it?
Ranger would be the class with the highest poison damage with the Poison Master trait. You can also stack a lot of poison with the bows and poison fields.
Necromancer and Thief also have many ways to inflict poison on the enemy.
If you want to focus on poison, then Ranger, Necro and Thief are pretty much your only choices. Engineer has a little access to poison, but not enough to focus your build around it.
Is it a good idea? That kind of depends on the latest patch and how Anet continues to tweak condition damage. You’ll probably want a second source of damage (physical, bleeding, whatever) to supplement the poison damage. But you can make it work, sure.
What about the Venommaster thief build. Is that no longer viable?
As engineer, remember Pistol#2 is poison.
It is very helpful on my condi-build engineer along with bleeds, burning and confusion.
Wishing I could afford a Torment sigil. heeh