Chameleon Skin is also a freebie: it’s a passive means that grants edge on Stealth Checks. No tactical implication; it just can make the yuan-ti improved at what it now does.
Extaminaars are the results of https://crithitceramics.com/the-importance-of-setting-in-a-campaign-a-guide-for-yuan-ti-pureblood-monks/