From the Publisher's website:
The Codex Venenorum — a venomous tome of poisoncraft from the quill of master poisoncrafter Nylson Veld — has long been sought by those who wish to work their subtle and deadly arts upon the unsuspecting. It is an outlaw tome, penned by a pragmatic poisoner whose decades of experience have yielded a lethal harvest.
Bringing the principles of poisoncraft to Dungeons & Dragons 4th Edition, the Codex contains detailed poison creation rules and over eighty sample poisons for use at any level, from the vile hopemelter to the subtle blue deception. Whether practicing mortal politics in the halls of power, or wielding an assassin’s blade on the battlefield, the Codex is your poisoned path to victory.