Circle of Phantasm Archdruid

Devil’s Sight. Magical darkness doesn’t impede the druid's darkvision.

Magic Resistance. The druid has advantage on saving throws against spells and other magical effects.

Multiattack. The druid makes two bite attacks or two Spectral Fangs attacks. 

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 5 (1d4 + 3) piercing damage plus 7 (2d6) poison damage.

Spectral Fangs. Ranged Spell Attack: +6 to hit, range 120 ft., one target. Hit: 16 (3d8+3) poison damage. If the target is unconscious due to the effects of Merrshaulk's Slumber, the damage caused by this attack does not wake the target.

Merrshaulk’s Slumber (1/Day). The yuan-ti targets up to five creatures that it can see within 60 feet of it. Each target must succeed on a DC 14 Constitution saving throw or fall into a magical sleep and be unconscious for 10 minutes. A sleeping target awakens if it takes damage or if someone uses an action to shake or slap it awake. This magical sleep has no effect on a creature immune to being charmed.

Spellcasting (Yuan-ti Form Only). The druid casts one of the following spells, using Wisdom as the spellcasting ability (spell save DC 13):

At will: animal friendship (snakes only), mind sliver, message, mage hand

3/day each: phantasmal force, suggestion

2/day each: hold person, darkness, invisibility

Change Shape (2/Day). The druid magically polymorphs into a monstrosity form—young kruthik, male steeder, or wretched sorrowsworn —or back into its humanoid form. Any equipment it is wearing or carrying is absorbed or borne by the monstrosity form (the druid’s choice). It reverts to its humanoid form when it dies. The druid’s statistics are the same in each form, except where noted in this stat block.

Change Shape. The druid transforms 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. If it dies, it stays in its current form.