You are considered Monsterfolk by other races even though you consider yourself as humanoid.

You are Medium (about 7–9 feet tall).

Your walking speed is 60 feet. Your climb speed is 60 feet. Your swimming speed is 40 feet.

You have Darkvision with a range of 60 feet. 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. While in darkness, you perceive your surroundings in a thermal spectrum, with living creatures and warm surfaces unhidden by magic or thermal camouflage appearing as heat signatures due to your pit organs, but you cannot otherwise discern color in darkness.

You reach maturity around 3 years old, and have immortal lifespan. You keep your youthful attractive appearance even as you grow older and more dangerous.

Lamia tend toward evil or neutral alignments, but the Lamia who choose to leave her lair to life with other races often adopt the alignment of their community.

Your Charisma and Intelligence both increase by 2. In addition, one ability score of your choice increases by 1.

Your forked tongue and pit organs are fine-tuned to living creatures, granting you the superior hunting abilities of a serpent. Additionally, you have proficiency in the Stealth and Acrobatic skill check.

Tail Sweep. Melee Attack Roll: Dexterity Modifier + Proficiency Bonus, reach 10 ft. Hit: (1d6 + Dexterity Modifier) Bludgeoning damage. Lamia use her snake body to strike her enemies feet in 5 ft diameter center from her body. If hit, target must make Dexterity Saving Throw: DC 10 + your Strength Modifier. Failure: On a failed save, the creature has the Prone condition.
Constrict. Strength Saving Throw: DC 10 + your Strength Modifier + your Proficiency Bonus, one Medium or smaller creature that you can see within 10 feet. Failure: The creature take (2d8 + your Strength Modifier) Bludgeoning damage, and the creature has the Grappled condition (escape DC 10 + your Strength Modifier).

Lamia are beautiful feminine humanoid above her waist, with long snake body below the waist, making them dangerous seductress for males. You have advantage on Charisma (Persuasion), Charisma (Deception), and Charisma (Performance) checks. Additionally you can cast Charm Person, Detect Thoughts, and Pass without Trace with your Charisma as Cantrip from level 1.

Your connection to the Dark Snake God Zehir give you proficiency in Arcana skill check.

You have disadvantage on Constitution saving throws against spells that deal Cold damage, and vulnerability to cold damage. Additionally, you also have disadvantage on Constitution saving throws made to withstand cold environments. You have immunity against poison attack, and immune to Poisoned condition.

You can speak, read, and write Common, Elvish, Gnomish, Orcish, Dwarvish, Abyssal and Draconic.