Poison is an ailment that deals chaos damage over time to the affected target. I've been playing a very similar build for the last 2 weeks, currently at 99, working on 100.
I have no idea if you are one of the two guys i already talked about that asked me about the build, if so ignore my post!
Some things that differ:
1) I am running Inpulsa's instead of Dendrobate. Dendrobate's usefulness is limited, as it only serves for 100% increased damage and 25% Duration (you are already capped at 100% Chance to poison) and i replaced it with Inpulsa's, which is able to apply incredibly huge Poison Stacks to Monsters due to Volkuur's (it also has a Life Roll, which is VERY scarce in the build). Then again, if you go for purely Shaper farming, i can see the Dendrobate having use.
2) I pathed very differently than you did in the Skill Tree. I went through the Shadow nodes, which are excellent and through the witch nodes. (Life and Flask Effectiveness).
The Flask Effectiveness also enables you to replace one of the Jewels with Conqueror'S Efficiency, which provides +1 Additional Arrow from Dying Sun, due to Flask Effectiveness. (Which is worth it for Tornado Shot at least) Due to the more widespread tree, i was also able to pick up a lot more Life Nodes, resulting in around 7k Life, realistically 6k life at Level 90. ( which, if needed, can be traded in against Jewel Slots, i only didnt take some 4 point Jewels because of the Level 100 grind and not needing the extra damage).
3) I did go for a +2 Arrow Elder Quiver, as i am going Tornado Shot and it is Clearspeed and Single-Target Damage at the same time.
4) I guess i also put a lot more Path of Exile currency into the build, corrupting myself a +1 Arrow Quill Rain and Temporal Chains on Hit Volkuur's.
Overall, really cool that somebody else is playing the build, was only a matter of time till people catched onto it!