Poisoned Weapons do not rely on Strength or Toughness to wound. They always wound on the fixed number given typically a 2+, 3+, or 4+. Everyone knows this part. What I see people forgetting is that if the strength of the wielder is the equal to or higher than the toughness of the victim, the wielder must re-roll failed rolls to wound in close combat.
Now this doesn't effect the poisoned shooting weapons of the Dark Eldar, but it does effect the multitude of poisoned close combat weapons that they get.
Now you simply look at something like Furious Charge. Furious Charge increases your strength characteristic by 1. So this would mean that Wracks with a second pain token charging into marines would get to re-roll every failed to wound roll. That is a 4+ with a re-roll the round you charged.
Now lets look at something a little more devious. Give your Haemonculi an Animus Vitae. This means that if he kills a model he has to pass a leadership test, and if he does he gains a pain token. I said model, not unit. Give him Flesh Gauntlet (poisoned 4+ instant death), or scissorhands (poison 3+ that grants +1 attack in addition to the +1 for extra close combat weapon).
Start your Haemonculi with a unit of wracks, and you instantly get furious charge. Now we have a Wracks assaulting on Inititive 5 WS4 and poison 4+ with a re-roll to wound. A Haemonculi Ancient with scissorhands is 6 attacks on the charge, wounds on a 3+ with re-roll and WS5.
