OK, so, Hell is now complete and things have evolved quite a bit; thanks to an item I was given out of the blue: Death's Web, and a near perfect one at that (49% poison damage reduction out of 50). Plus other gifts, again out of the blue, but here is how the character stands right now, gear wise:

* notable charms: 3 with +1 to all skill trees, Gheed's, torch, anni -- to be honest I don't recall the exact stats;
* helm: a Shako, socketed with a perfect "on level up" poison rbf (therefore +5% poison damage, -5% poison resist to enermies);
* body armor: self-made Bramble, could be better (39% extra poison skill damage out of 25-50, lvl 16 Thorns out of 16-21, picked the low end here);
* rings: Ravenfrost, plus a "random" rare ring providing bonus AR and dex, 27% lightning resist,
* amulet: Mara 23;
* boots: War Traveler 48%;
* belt: Arachnid Mesh (war), upgraded Goldwrap (mf);
* weapon slot 1: Death's web, Homonculus;
* weapon slot 2: Fleshripper socketed with a Shael, Homonculus.

Merc is an act 2 might merc equipped with an ethereal upgraded Duriels, Vampire Gare and an ethereal Obedience thresher.

Death's web is what changed everything to me; I knew for a fact that if I could break poison immunity with Lower Resist, the -x% to poison resist of this weapon would only apply AFTER the immunity has been broken... And it shows. I end up using my second weapon slot only for tough, poison immune encounter and for fun, because frankly, at this stage, this build kills more than 90% of foes out there with a simple LR/PN. For the others (particularly the poison immune even after LR) I still have Fleshripper at my disposal plus, of course, those other curses including AD and Dim Vision.

The result of all this is that my skill points are not quite optimized but that is the problem of a build being so "one click" that you lose the global side of things. One thing I will definitely do for sure is again max out all poison skills. In particular, the AR bonus of Poison Dagger is reaaally significant. 69% to hit Hell Baal is not bad for a necro, i dare say... Especially since (as far as I could read) this is calculated BEFORE the -x% to target defense of Fleshripper applies (although it is halved for at least act bosses).

Yeah... Death's Web litterally turned my planned build inside out... One result is that I have no CtA but I don't really need it!