Shapechanger. The yuan-ti can use its action to polymorph into a Medium snake, or back into its true form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn’t transformed. It doesn’t change form if it dies.

Innate Spellcasting (Yuan-ti Form Only). The yuan-ti’s innate spellcasting ability is Charisma (spell save DC 13). The yuan-ti can innately cast the following spells, requiring no material components:

At will: animal friendship (snakes only)

3/day: suggestion

Magic Resistance. The yuan-ti has advantage on saving throws against spells and other magical effects.

Acid Slime. 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 within 5 feet of it, or is hit by its constrict attack takes 5 (1d10) acid damage.

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

Shed Skin (1/Day). 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.

Malison Type. The yuan-ti has Human form with one or more serpentine tails.

Multiattack (Yuan-ti Form Only). The yuan-ti makes two melee attacks or two ranged attacks.

Bite (Snake Form Only). Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 5 (1d4 + 3) piercing damage plus 7 (2d6) poison damage.

Scimitar (Yuan-ti Form Only). Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage.

Longbow (Yuan-ti Form Only). Ranged Weapon Attack: +4 to hit, range 150/600 ft., one target. Hit: 6 (1d8 + 2) piercing damage.