Originally Posted by Oblivion
2)Insidious Poison, the damage it deals is so very low(At rank 5 its 2.8 dps for 10 seconds which is 28 damage) and it only applies on hits with skills so using a faster weapon and use left click attacks aren't even a viable strategy.
Viper Venom, same as above really, its damage isn't too great.
I don't know anything about rogue or how these skills scale, but as a general rule it is better to have 2 stacking skills than just one skill, because it is considerably cheaper to invest in them for the same or similar reward.
edit: 28 damage at rank 5 seems horribly low even for what iirc is a free mana passive. However, it has to be balanced against the saving in intelligence stat points which can then be put into dex and what flow-on that has to other skills. A very interesting skill to balance!