Yuan-ti
The people known as yuan-ti were not always the way they are today; snakelike, transfigured, magic in their souls and poison in their blood. Appearing in many places throughout the world, it's said that these people descend from human tribes who have found magical means to "improve" themselves.
It is true that yuan-ti descend from humans, which is why they resemble them so closely. Some yuan-ti are indistinguishable from humans but for their snakelike slitted pupils. Others, who have been transfigured beyond humanity, resemble human-sized, human-armed snakes; or those who have gone steps even further grow multiple snake heads, as a hydra.
Despite their glorious transfigurations, however, only the most-human of yuan-ti can reproduce with each other. Those who slither too far into serpentine biology become unable to continue their lineage; while they may rule over lesser yuan-ti, the two sects need each other to survive while still proceeding toward their goal of snake-like perfection.
Though most yuan-ti do not have a means to deliver it, their blood is poisonous. Some have been known to intentionally distill their own blood for malicious use.
It is not known why yuan-ti are exclusively descended from humans; and not ever from elves or dwarves or tabaxi or any others. It is possible that only humans have a flexible enough biology to enmesh with that of snakes.
In different eras and places, yuan-ti tribes have seemingly appeared and reappeared independent of one another, in all cases sharing the same basic traits. Groups of humans who wish to transfigure using certain magic, imbuing their bloodlines with ancient genes; always found in dangerous and wild places, jungles and swamps away from civilization.
On Des Forabis the yuan-ti appeared some millennia ago in the jungle Hezrah, which stretches along the continent's southernmost coastline. Isolated by unforgiving terrain, the yuan-ti who live there have usually kept to their own devices... but on occasion, groups from the region have ventured north through Coterra, Khollaja, and other nearby countries to wreak havoc and attempt to exert dominion.
For this reason, the humanlike yuan-ti and their monstrous, transfigured siblings are widely seen as villainous. Friendly relations with the tribe are scarce and most who live near the jungle merely hope that the snakefolk continue to keep to their isolated ways.
As a lesser yuan-ti, you are mostly human, but you've been born into a sub-species with motives beyond humanity. Your snake blood can be less-than-obvious, but it is undeniable, and you likely grew up around other yuan-ti who have ascended further beyond humanity, their nature more obvious and more monstrous with every step.
Not all yuan-ti are evil, but those who embrace their "true" forms; as those creatures named malisons, and anathema, and broodguards, and more; tend to become that way, as transfiguration changes their mind, brings madness, and kills empathy. You might consider evolution as a yuan-ti to be a near-divine goal of yours; or you might consider it to be a doomed fate, something you'd like you and your loved ones to avoid if possible.
It is not often that the yuan-ti of Hezrah send their own into the wider world and even rarer that any yuan-ti families live outside their homeland. If you are on a quest elsewhere, you surely have a very good reason for it.
Regardless of your own alignment, it's likely that people in other civilizations who find out your true nature will consider you a villain or monster, thanks to your species' own history.
Ability Score Bonus. You gain a +2 to Charisma and a +1 to Intelligence.
Age. Yuan-ti age at the same rate as regular humans.
Size. Your size is Medium. Male and female yuan-ti are the same size and shape as humans.
Speed. Your base walking speed is 30 feet.
Darkvision. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.
Venomous Spellcasting. You know the poison spray cantrip. You can cast animal friendship an unlimited number of times with this trait, but you can target only snakes with it. Starting at 3rd level, you can also cast suggestion with this trait. Once you cast it, you can't do so again until you finish a long rest. Charisma is your spellcasting ability for these spells.
Magic Resistance. You have advantage on saving throws against spells and other magical effects.
Poison Immunity. You are immune to poison damage and the poisoned condition.
Cold-Blooded. You have an ectothermic physiology and rely on environmental heat sources. When you are in a freezing environment, your base walking speed is decreased by 5 feet and you have Disadvantage on Intelligence ability checks and saving throws. When you are in a very hot environment, your base walking speed is increased by 5 feet and you have Advantage on Intelligence ability checks and saving throws.
It is true that yuan-ti descend from humans, which is why they resemble them so closely. Some yuan-ti are indistinguishable from humans but for their snakelike slitted pupils. Others, who have been transfigured beyond humanity, resemble human-sized, human-armed snakes; or those who have gone steps even further grow multiple snake heads, as a hydra.
Despite their glorious transfigurations, however, only the most-human of yuan-ti can reproduce with each other. Those who slither too far into serpentine biology become unable to continue their lineage; while they may rule over lesser yuan-ti, the two sects need each other to survive while still proceeding toward their goal of snake-like perfection.
Though most yuan-ti do not have a means to deliver it, their blood is poisonous. Some have been known to intentionally distill their own blood for malicious use.
It is not known why yuan-ti are exclusively descended from humans; and not ever from elves or dwarves or tabaxi or any others. It is possible that only humans have a flexible enough biology to enmesh with that of snakes.
Yuan-ti in the World
In different eras and places, yuan-ti tribes have seemingly appeared and reappeared independent of one another, in all cases sharing the same basic traits. Groups of humans who wish to transfigure using certain magic, imbuing their bloodlines with ancient genes; always found in dangerous and wild places, jungles and swamps away from civilization.
On Des Forabis the yuan-ti appeared some millennia ago in the jungle Hezrah, which stretches along the continent's southernmost coastline. Isolated by unforgiving terrain, the yuan-ti who live there have usually kept to their own devices... but on occasion, groups from the region have ventured north through Coterra, Khollaja, and other nearby countries to wreak havoc and attempt to exert dominion.
For this reason, the humanlike yuan-ti and their monstrous, transfigured siblings are widely seen as villainous. Friendly relations with the tribe are scarce and most who live near the jungle merely hope that the snakefolk continue to keep to their isolated ways.
Yuan-ti Player Characters
As a lesser yuan-ti, you are mostly human, but you've been born into a sub-species with motives beyond humanity. Your snake blood can be less-than-obvious, but it is undeniable, and you likely grew up around other yuan-ti who have ascended further beyond humanity, their nature more obvious and more monstrous with every step.
Not all yuan-ti are evil, but those who embrace their "true" forms; as those creatures named malisons, and anathema, and broodguards, and more; tend to become that way, as transfiguration changes their mind, brings madness, and kills empathy. You might consider evolution as a yuan-ti to be a near-divine goal of yours; or you might consider it to be a doomed fate, something you'd like you and your loved ones to avoid if possible.
It is not often that the yuan-ti of Hezrah send their own into the wider world and even rarer that any yuan-ti families live outside their homeland. If you are on a quest elsewhere, you surely have a very good reason for it.
Regardless of your own alignment, it's likely that people in other civilizations who find out your true nature will consider you a villain or monster, thanks to your species' own history.
Yuan-ti Traits
Ability Score Bonus. You gain a +2 to Charisma and a +1 to Intelligence.
Age. Yuan-ti age at the same rate as regular humans.
Size. Your size is Medium. Male and female yuan-ti are the same size and shape as humans.
Speed. Your base walking speed is 30 feet.
Darkvision. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.
Venomous Spellcasting. You know the poison spray cantrip. You can cast animal friendship an unlimited number of times with this trait, but you can target only snakes with it. Starting at 3rd level, you can also cast suggestion with this trait. Once you cast it, you can't do so again until you finish a long rest. Charisma is your spellcasting ability for these spells.
Magic Resistance. You have advantage on saving throws against spells and other magical effects.
Poison Immunity. You are immune to poison damage and the poisoned condition.
Cold-Blooded. You have an ectothermic physiology and rely on environmental heat sources. When you are in a freezing environment, your base walking speed is decreased by 5 feet and you have Disadvantage on Intelligence ability checks and saving throws. When you are in a very hot environment, your base walking speed is increased by 5 feet and you have Advantage on Intelligence ability checks and saving throws.