The study of poisons and drugs extends far beyond the simple crafting of deadly chemicals. It takes no study to enter a general store, buy some rat poison, and jam it down an enemy's throat. The skill comes in getting away with it. This is not referring to some daring escape from angry guards. Nor some guarantee that the victim does not gag it back up. The skill is in the engineering of the compound so that no one even knows the toxin has been administered until the perpetrator is long gone and never even suspected. As well as so embedded in the victim's biological systems that he cannot be saved.
A master toxicologist can engineer an attack with such suddenness and mystery as to be on a par with magic. The very squeak of an overtone produced by a musical instrument may trigger a muscular cringe, causing a physiological spike of seemingly negligible effect. But there may already be several elements of the final compound in the victim's body; each one ineffectual until completed by the simple heating of the skin from a blush of embarrassment - the final element. The chain reaction begins; the victim withering and dying before the eyes of a horrified crowd; the musician dragged off for interrogation, pleading his innocence in vain.
Now of course, there is something to be said for the learning of different sources of the toxin itself. And they are found in every class of flora, fauna, mineral and gas; as are the reagents which allow the "fine tuning" of the toxin's effect envelope. Even the novice can create deadly compounds. But they are easily detected, not only by the look and smell before being planted in food or drink; but by the look and smell of the food and drink after being spiked.
Also, there is the potency concern. Generally, the more tailoring a compound undergoes, the less potent the final toxin will be. Increased skill will allow a greater degree of purity, which equates to both greater potency and shelf life, in addition to the added control over secondary effects, triggers, delay and disguised origin. These skills are what the toxicologist truly develops as he grows in skill.
This "tailoring" and "engineering" is accomplished through the use of reagents. These substances are not generally toxic in and of themselves, though they are rarely beneficial either, but they are the means to control the release and reaction of the toxin. An unskilled poisoner can smear a toxin on the blade of his dagger, and is every bit the threat to his target that a devious master is. But the toxin is plain to see. So an adversary may change his mind about staying to fight, or may adopt a different fighting style that makes the presence of the toxin less likely to be significant.
With a little more skill, the poisoner may include a masking agent, to hide the discoloration of the compound. As well, he may blend a thinning and binding agent to make the compound smear as easily as water, but still stick to the blade. Other masking agents will neutralize smell, or glare from the coating.
Legend speaks of a master that acquired a sample of a target's own mucus and reverse engineered a toxin so that, even after all the other elements were in place, the man still needed to sneeze to introduce the last element of the compound to trigger the poison. Obviously the target's own mucus was not toxic to him. But the master had found a capability, in its texture, to immediately seal away an inhibiting reagent. The target actually had the entire toxic compound in his body, but one element was blocked by the presence of this inhibitor. So when the man sneezed, the sealing capability of his own mucus blocked the inhibiting agent, allowing the full blending of the toxin.
The man had actually been poisoned halfway around the world. But had been in such good health that he had not sneezed until he reached a city where certain pollens triggered his allergies, causing him to sneeze. The Toxin Master had done his research on his target and learned of this allergy. Panic ensued, the population believing all kinds of exaggerated theories about what killed the man, never knowing it was an element in a drink in one tavern; the prick of a dart in another; a spice in a meal at an inn; an oil in a massage at a brothel; a sample of perfume in another; and a small stain on a chilled cloth he wiped his face with on a hot day.
Now of course, it is rare that such a degree of misdirection is required. Politics were the guiding purpose in that scenario. Most folks simply want an edge in a fight, or a quiet strangling death in an alley to someone who has bullied them all their life. But perhaps a powder to be blown in the face is a better method than a coated dagger. Or a mist from a plant sprayer instead of something hidden in the gravy on a man's potatoes.
Also, death may not be the intention. Perhaps an inn owner would like a new rival discredited. It would be very handy if it appeared that several customers got food poisoning from the man's stock, but no one needs to die of it. In these cases, reagents will be necessary to alter the form of the toxin to make it easier to administer by the chosen method. As well as to make the debilitating result more closely resemble the bacterial nature of food poisoning, rather than an outright toxic chemical.
Because the interactions between mortal cultures have been so strained, there is little sharing of information academically. As a result, there are virtually no assumptions made about what sources yield what toxins and/or reagents. New discoveries are being made every day in one corner of Idalos or another. The skilled toxicologist is the one that makes these discoveries. Learning, for example, that some mineral, believed to only be used to make dyes, can also be dissolved in water laced with the rinds of a local fruit, and that the resulting gas is a paralytic poison. But that this same rind, when NOT mixed with this mineral, is also an antitoxin to that very same poison.
This is just an example of how wide open the world of toxin and reagent discovery still is. Where one city may insist that only arboreal or fungal sources yield nerve toxins, another city may find such sources to yield primarily skeletal-eroding versions. One spider's venom causes nerve spasms that can be directed and perfected to stop a heart, where a spider on the other end of the continent causes brain damage and psychosis.
It's all in the creativity of the theory and the care taken to research and test it. Good luck.
Blood Toxins: The classic. This is smeared on a weapon, and gets in the blood stream from a cut. Or could be simply smeared by hand on an open sore. Responds to proteins in the blood. Be sure you do not have a cut on that hand. Here again, reagents can hold its effect until the blood carries the toxin to its desired organ.
Airborne: These are inhaled as gases or mists. Most often, these need to be tailored to dissipate quickly and only respond to wet internal tissue, like lungs or saliva. Otherwise, it can be very dangerous to assume that every wisp of an airborne toxin was actually inhaled by the target. Keep a cloth handy to cover your own mouth for a few minutes.
Ingestion: The other classic. Slipped into food or drink and most often tailored to be triggered by stomach acid. If it responds to saliva, a significant amount of the dose could be spit back out, resulting in failure. Pretending to swallow is a tactic many food testers employ when they are in on a plot.
Contact: Self-explanatory. This is frequently a liquid that soaks into skin. However, an airborne type may be blown onto a target. Most likely the eyes. Often hidden on towels or rags, possibly slipped into the inside of coat sleeves.
Examples of Reagents
Thinners and Thickeners: As it suggests, these are simply to adjust the texture of the toxin to make it more versatile in delivery. What is normally a blood toxin, could be thinned to be able to be sprayed as a mist. Or an airborne toxin could be thickened to apply to a blade.
Inhibitor: An element that prevents some stage of the toxin's completion or release. Commonly used to make it difficult to know when the target was poisoned. Also, to prevent the effect from manifesting before it reaches the target body part.
Trigger: The element which is going to react with the compound to unleash the toxin within the target. It is often not part of the compound itself. For example, in the Ingestion example, the "trigger" is the stomach acid.
Binder: An element that keeps the properties of two different reagents or toxins together, so the effects of both will be unleashed simultaneously. It usually has no direct impact of its own as far as the nature of the toxin's effects go.
Combinant: An element that actually blends the properties of two different reagent or toxins. This is used instead of a binder when it does not matter how soon the properties are blended.
Accelerant (or catalyst): Basically the opposite of an inhibitor. It speeds up the chemical reaction of two or more different combined elements.
Metabolizer: An element that encourages the generation of whole new elements within a target. For example, a fungus on the trunk of a tree secretes a metabolizer that causes the tree to synthesize an inhibitor, in an attempt to block the incursion of the fungal growth. An additional fungal enzyme transforms this inhibitor into a food source for insects, whose depravations soften the wood, allowing the fungus easier access. These also are the bases for secondary effects. The metabolizer generates some new element which then reacts to an additinal part of the compound included for that very purpose. This is how the initial episode of, say, paralysis, is followed by weeks of confusion.
These are, of course, just a few examples of the discoveries being made. New theories are being put forward all the time.
The student has progressed to the manufacture of basic toxins. He has not yet had cause to learn a great deal about reagents, beyond triggers, thickeners and thinners. He is experienced with basic pieces of lab equipment, and may even have ideas of new tools and processes. For safety's sake, he is not trying to expand his grasp of different sources beyond the one or two that first got him interested. Once he gets those down pat, he will venture cautiously into new territory.
A whole new world opens up to the toxicologist. He has learned enough to know that he hardly knows anything at all. The safety lessons he has ingrained into his procedures benefit him greatly as he starts to dabble with new things. But it will be a long hard road, with each new source and reagent application he discovers. Care and testing is paramount. Strangely though, he finds that after a recent lab mishap, he did not suffer quite such an effect as he'd feared. Could he be developing a resistance? It would only be a slight one, and only to the products he's been working with for a while. He also comes to realize that chemical impact does not always have to be debilitating or deadly. He begins to work on drugs and antidotes. He also finds the potential for secondary effects opening up.
The poisoner is energized to find his resistance becoming more pronounced. This enthusiasm is diminished though, when he discovers the meaning of the word "withdrawal", as it pertains to his drugs. There is no longer any limit to what natural sources he can work with, but he is clearly better at the old ones than the new ones. But he is able to make use of sources from pretty much anywhere, with testing. His toxins have created a demand for his antidotes, and the grim realities of a world at war have also generated a demand for his feel-good, or performance enhancing, drugs. Depending on his morality, he may or may not wish to make his drugs less addictive.
Just when the poisoner thought he was at the top of his craft, a new element is introduced. Fractive elements. Where immortals have died, or from the bodies of those imbued with immortal powers comes a new reagent and goal to work towards... Mutagens! Found within the very soil and seed of fracture sites, he learns of supernatural potential. Creatures bent or resurrected by immortal will may hold secrets to compounds capable of unlocking spectacular abilities. Or they may hold cursed afflictions of horrific fates. Theories abound that some of the horrors walking Idalos today originated in the minds of mortals, and not immortals. And now, only such bizarre new toxins hold any real threat of accidental poisoning for the Toxin Master.