Venemous Totem is a rogue specific item from Blackwing Lair that is intended to increase the chance to apply poisons to your target by 30%. This interaction is currently not working at all with the Deadly Brew rune. When the trinket is activated, poison application chance is the exact same as not having the trinket active at all. This can be supported in logs:
One log shows the normal proc rate without the trinket being used which shows a 70% proc rate of Instant Poison. There are 107 Melee Hits and 66 Mutilate hits. There are 122 Instant Poison hits.
The next log shows the 20 second window that Venomous Totem was active. There were 35 Melee hits and 18 Mutilate hits, but only 40 Instant Poison hits which results in a 75% application rate when the rate should be ~100% with the trinket active.
I can not include the links to these logs due to forum rules but the data is consistent between many rogues.