Patch 3.1.0:
Increases the chance to apply Deadly Poison to your target by 10% and the frequency of applying Instant Poison to your target by 50%.
The frequency of applying Instant Poison by 50% does not mean its a +50% increase to the proc chances.
i.e. it WON'T make Instant Poison proc 70% of the time. That would be rediculous.
It makes the proc happen 50% more often.
Instant Poisons proc chance is 20%, so
1.5 * 20% = 30%
At first glance it doesnt look any different than the old version of the talent.
But in Patch 3.1.0, Instant Poisons and Wound Poisons will proc based on the weapon speed (Currently normalized to 1.4 speed daggers).
With that in mind, here are the 3.1.0 Instant Poison proc chances WITHOUT the talent:
1.3 Speed - 18.57%
1.4 Speed - 20.00%
1.5 Speed - 21.43%
1.6 Speed - 22.86%
1.7 Speed - 24.29%
1.8 Speed - 25.71%
2.6 Speed - 37.14%
2.8 Speed - 40.00%
3.1.0 Instant Poison proc chances WITH the talent:
1.3 Speed - 27.86%
1.4 Speed - 30.00%
1.5 Speed - 32.14%
1.6 Speed - 34.29%
1.7 Speed - 36.43%
1.8 Speed - 38.57%
2.6 Speed - 55.71%
2.8 Speed - 60.00%
Just a FYI, like I said earlier the same math will apply for Wound Poisons.
So while I'm at it, here's a list for the proc chances of Wound Poison:
1.3 Speed - 46.43%
1.4 Speed - 50.00%
1.5 Speed - 53.57%
1.6 Speed - 57.14%
1.7 Speed - 60.71%
1.8 Speed - 64.29%
2.6 Speed - 92.86%
2.8 Speed - 100.00%
Expect to see Combat rogues kick ass in 3.1.0 regardless whether they have this talent or not :)