Monster HD advancement and SA

Hello all fellow gamers. My cunundrum happens to be that I took a wyvern, and gave it an extra HD. This turned out to increase it's size to huge, it strength score by 8, con by 4, and Dex -2, plus all the -1 size to AC and attack. Now, the problem is that I'm not sure that the poison damage increases from the usual 2d6/2d6 to 3d6/3d6. While reading the MM, it said that when a creature increases it's size, all of it's special abilities, attacks and damage, increase one category, but I wasn't sure if there was a restriction on poisons in particular or not. I'd appreciate any answers. Thx.

Branok

Hmm, I tend to think it would increase the damage the poison does, but can't think of anything off the top of my head that expressly says one way or the other.. but compare the poison strengths of different sized vermin (giant spiders, centipedes etc).. different sizes of those are listed with different strength poisons. So from that perspective it makes sense even if it does seem a bit nasty.

Remember, the DC is raised too.. 10 + 1/2 racial HD + relevant ability mod. So if its con based (as many are) it gets +2 from the change to con, then it gets +some more from the HD increase.

I'd actually increase it to 2d8, not 3d6. I'm basing that ruling on the way the damage changes for a monstrous spider and a monstrous scorpion as they increase in size (MM, pg.288).

And the DC will definitely go up by 3 due to the HD and Con increase.