Toxicaster

Magic is a complicated tangle of energies, it is a miracle that any body is able to channel just a small fraction of that potential and create reactions. For most beings, raw arcane energy brought into the self would overload their neurons and melt their vascular system. However, when one is adapted to compartmentalize dangerous materials and safely expel them - they gain a distinct advantage. Since their system distills and creates powerful toxins, it can too draw on and imbue those same glands to also ingest the latent magic around them¹. As such, it is only the peoples capable of producing venom or poison that can become toxicasters - and thus make up the vast majority of magic users, even post-Toxin Wars.

FORMS

Also sometimes termed as 'classes', toxicasters tend to be specialized around certain mystic capabilities depending on the strength of their toxins at birth and the ways in which they choose to wield their magic. These two factors are what result in the 6 spheres of magician we associate with toxicasters.
Sorcerers: Those born with naturally strong toxins use them early and repeatedly to great effect. However since these individuals are incredibly talented from the start, they usually stick to one specific genre of spell and utilize only that for their entire lives. This repetition does make up for the lack of variety though, as the intimacy with which sorcerers know their spells allows for usage of them akin to a master captain making their massive vessel dance and weave through a pod of skyswimmers.
Clerics: The gods are to be avoided at the best of times. They are well documented for their mercurial nature, and thus the danger of interfacing with them is high. However, there are ways to channel their power. Toxicasters who have decently potent toxins will seek to strengthen their foundation through reaching out to touch these beings that control aspects of the world. Through using symbols and specific wards, as well as only stealing from part of the god's domains they can avoid the attention of the god. Allowing them to channel divine might without the notice of such powerful, precocious deities. But warnings abound around using certain spells, and especially around burning one's toxin reserves when walking the path of a cleric - lest you garner the attention of divinity.
Warlocks: On the other hand, those born with weak poison but with brave hearts may wish to increase their potency. These toxicasters will step further into the waters of risk than clerics - they will directly face the gods and ask to deal with them for a piece of their power. These are the rarest class, about as rare as dreamwalkers are in the non-toxicaster peoples, for that very reason. And much like dreamwalkers, those that live through the ordeal of gaining their power deserve much respect for their skill and trepidation.
Paladins: There are those who are born with toxins as potent as sorcerers but without the talent to wield it. This wild and chaotic power is something that requires an anchor or the caster may become lost to its tide. So, these individuals have come up with the anchor of a mantra or oath. This rigid structure allows them to guide their power safely and use it with great force, much like how the pressure of water increases when narrowed through pipes.
Bards: Similarly to the paladins, although with not as potent toxins, Bards will use a repetitive anchor to guide their magic's use. However unlike the paladin, the anchor itself does not effect the form of the magic. Rather it is merely a ritual to help focus the wielder. Its form does not matter, and there are bards on record using everything from the most complicated instruments to simple rhythmic dances.
Wizards: Those with especially weak poison can overcome it with time, effort, and most of all study. Through understanding the precise metaphysical strands that are pulled on as the other classes cast their spells, wizards can begin to expand their own ability while still having weak toxins. The toxin is merely the catalyst they use to jump start the reaction, and it is their intellect and comprehension that envisions the conduit for the mana to travel and form the spell.

Article contributed by Hinpe Rogne, Head of Arcana.

Footnotes

¹Now I have made arguments in a recent seminar that the ritualistic nature on a cellular level of producing the toxins is what starting the integration of magic into the body rather than being folded into the poison or venom at a higher level of production, but this is still contested.

Mechanical Clarifications

Being one of the classes listed as a Toxicaster means that you have to choose one of the toxic races in the Garragunya setting to play as said classes. They are: Corroboree, Durang, Wirraga, Shrike, Uroda, Marrayagong, Chleana, Horrida, Iruka, Chromador, Walumil, and the Pitohui.

Mechanical Additions

All Toxicaster classes have access to 3 additional spell slots, of any spell level available to the player at their character level. However, reaching into the deepest reserves of your toxins to cast additional magic is not without consequence.
Burning through the first Toxic Slot will give you 2 levels of exhaustion.
Burning through the second Toxic slot results in 2 more levels of exhaustion.
And if you use your last Toxic Spell Slot, you won't be able to cast magic ever again.
Having burned all of your body's reserves and every gland that produces it for the very last drops of toxin in your system for that last hurrah, your character will lose all levels in their class. They will be unable to gain levels in that class or any of the other toxicaster classes for the rest of their life. They can however, become dreamwalkers just like everyone else.