Crap, fudged up this post on accident
i'll repost it as much as I can remember
-enemy resistance is a new property on items of v1.10
much like how you'd take more lightning damage if you had 10% lightning resistances than if you had 75% lightning resistances, deaths web lowers the monster's (or players) poison resistance automatically, thus dealing it more damage
When a deaths web drops the item is granted a random number between -40 through -50, and this represents the amount of poison resistance that the wand will lower.
Sorry about messing this post up I was trying to quote myself and I hit edit on accident, and absentmindedly saved the changes