So let’s say for example, you have of the abyss on a weapon, and weapon damage% to doom bolt on another item. Does Doom Bolt proc Of the Abyss res nerf?
yes
And can a similar thing happen for ADctH?
yes
Hi Gnomish, perhaps a stupid question, is %WD necessary for the DR on an of the abyss item to proc it? Eg if you would use devouring swarm all the time as only skill, using a green of the abyss weapon. Pretty exotic but to understand the mechanics, thanks 
yes %weapon dmg is required
the debuff in this case is considered a flat stat of sorts, like the same if it was +12 flat dmg, and gets handled like normal "weapon direct flat"stats does thus requires weapon dmg to apply
similarly for ex Judicator rings, or Viper devotion vs Ultos devotion; viper %RR is a regular passive stat on a node but Ultos is part of a proc so is baked into the skill itself, but Viper being a passive means it requires weapon dmg
Likewise for abyss, plaguebearer etc affixes on weapons, and in addition to that since it’s a native flat stat direct on the weapon; has to be attacked with the hand it’s specifically in
^this means if you’re dualwielding, and have abyss in offhand slot, only skills/attacks with the lefthand will apply it
If I remember correctly you need >=100% WD on skill to fully apply those debuff effects. For example, 50% WD only apply half debuff of Viper.
correct
and debuff effect caps at 100%, wont scale higher with ex 300%wd attack skills
Thanks guys!