Euthanizer (25% more damage against enemies suffering from poison.) (Rank 3)
Critical Accumulation (Rank 2)
You can find the skill "Euthaniser" in these legendary gloves.
Feel free to replace Critical Cumulation with Mitigation from Death if you have trouble staying alive.
Captian Hunter (Rank 3)
Emergency Status (Rank 2)
Splash Range [Splash Boost] (Rank 3).
Poisonous Lead (Rank 2)
Eagle Eye [Sharp Eye] (Rank 3)
Horse Cure (Rank 2)
Dum-Dum Bullets (Rank 2)
Bloodlust (Rank 2)
Bone Splinter (Rank 2)
Killing Spree (Rank 3)
"Killing Spree" is the perfect mod for any damage build, but "Fortress" and "Striga" can also be extremely helpful.