Armor Class 15
Hit Points 127 (15d10 + 45)
Speed 40 ft., climb 30 ft.
Skills Perception +7, Stealth +6
Damage Immunities poison
Condition Immunities poisoned
Senses Darkvision 60 ft., passive Perception 17
Languages Abyssal, Common, Draconic
Challenge 7
Magic Resistance. The yuan-ti has Advantage on saving throws against spells and other magical effects.
Multiattack. The yuan-ti makes two Bite attacks, and it can use Spellcasting to cast Suggestion if available.
Bite. m +7, reach 5 ft. Hit: 11 (2d6 + 4) Piercing damage plus 10 (3d6) Poison damage.
Constrict. str DC 15, one Large or smaller creature within 5 feet. 28 (7d6 + 4) Bludgeoning damage. The target has the Grappled condition (escape DC 14), and it has the Restrained condition until the grapple ends. Half damage only.
Poison Spray (Recharge 5–6). con DC 14, each creature in a 30-foot Cone. 21 (6d6) Poison damage, and the target has the Poisoned condition until the end of the yuan-ti's next turn. While Poisoned, the target has the Blinded condition. Half damage only.
Shape-Shift. The yuan-ti shape-shifts into a Large snake or returns to its true form. If it dies, it stays in its current form. The yuan-ti's game statistics are the same in each form, except where noted. Any equipment it is wearing or carrying isn't transformed.
Monster Manual (2024), p. 345