Volo’s Guide to Monsters’ treatment of the yuan-ti is heavily lore-focused, with a section, useful to dungeon masters, on how to design a yuan-ti temple-city. From a tactical standpoint, the only additions are five new variants (!) and a brief subsection headed “Unusual Abilities.”
Unusual Abilities offers four traits that DMs can use to customize an individual yuan-ti or a group of them:
- Acid Slime gives the yuan-ti a corrosive coating, lasting one minute, that inflicts 1d10 acid damage against a grappled opponent or one who strikes it with a close-range melee attack. It’s a bonus action, and yuan-ti don’t get any other bonus actions, so this is a free supplement to the yuan-ti’s action economy. It’s all benefit and no downside, so the yuan-ti will use this feature on its first turn.
- Chameleon Skin is also a freebie: it’s a passive ability that grants advantage on Stealth Checks. No tactical implication; it just makes the yuan-ti better at what it already does.
- Shapechanger, for the yuan-ti pureblood, comes with the same disadvantages as it has for the yuan-ti malison and yuan-ti abomination. Skip it.
- Shed Skin is another all-benefit, no-downside feature, letting a grappled or restrained yuan-ti slip free without a skill or ability check. It costs only a bonus action, which is no cost at all, since the yuan-ti has no other bonus action to give up. A yuan-ti with this trait will use it anytime it applies.