Now I just recently got my Tyranid codex, and I was thumbing through it when I noticed that Carnifexes can take Toxin Sacs, which confer the "poisoned (4+)" rule on their CC attacks. Now perhaps I am being dense here, but Carnifexes have Str 9, which means that against just about everything in the game, they will wound on 2+, so wouldn't taking toxin sacs be paying to nerf the 'fex?

If the poisoned rule said that they wound on X+ unless the comparison of strength and toughness would be better, then I could (maybe) see taking them (particularly with the additional component of poisoned allowing you to re-roll failed wounds if your Str is greater than the target's toughness). But otherwise how on earth is this a viable option?

Also, if one happened to have a 'fex with toxin sacs already, do you think WYSIWYG would demand that it be given the upgrade?