Your dexterity score increases by 2. Your charisma score increases by 1.

Yuan-ti have a lifespan really similar to human's, living less than a century.

Yuan-ti are usually evil, and care very little about law or chaos, being mostly neutral evil.

Malison Yuan-ti are the same height as humans, without mesuring their tail

Your base walking speed is 30 feet

As a bonus action, the yuan-ti can coat its body in a slimy acid that lasts for 1 minute. A creature that touches the yuan-ti, hits it with a melee attack while withing 5 feet of it, or is grappled by the yuan-ti takes 1d10 acid damage

You can use your action to make a melee attack using your fangs. An enemy hit by this attack takes 1d4 piercing damage + 1d6 poison damage.

The yuan-ti has advantage on Dexterity (Stealth) checks made to hide.

The yuan-ti targets a creature it can see within 60 feet of it. The target must succeed on a Wisdom saving throw or be transformed into a Tiny poisonous snake, as if affected by the polymorph spell. The save DC is the same as the DC of your natural spellcasting trait.

The yuan-ti can shed its skin as a bonus action to free itself from a grapple, shackles or other restraints. If the yuan-ti spends 1 minute eating its shed skin, it regains hit points equal to half its hit point maximum. You can only use this trait once per day

The yuan-ti targets a creature it can see within 60 feet of it. The target must succeed on a Wisdom saving throw or feel an intense urge to avoid snakes and snakelike creatures (including yuan-ti), as if affected by the antipathy effect of an antipathy/simpathy spell. The DC is the same as the DC of your natural spellcasting trait.

The yuan-ti transforms a pile of sticks, arrows, or similar sized pieces of wood into a swarm of poisonous snakes. The swarm acts as an ally of the yuan-ti and obeys its spoken commands. The swarm remains for 1 minute, after which it turns back into the original materials

The yuan-ti has advantage on saving throws against spells and other magic effects

You know the cantrip Poison Spray. You can cast Animal Friendhip an unlimited amount of times, but it can only affect snakes. At 3th level you can also cast Suggestion once per long rest. Charisma is your spellcasting score.

You're capable of seeing up to 60 feet in dim light as if it were regular, and that same distance in darkness as if it were dim. You cannot see colours, but rather a scale of gray.

You are immune to poison damage and the "poisoned" condition.

You have resistance to poison damage. You also have advantage on saving throws to avoid or stop the poisoned condition on yourself.