Blessed Serpent of Sseth

Blessing of Sseth.  The serpent has advantage on Wisdom (Perception) checks and saving throws against being charmed or frightened. It also gains resistance to poison damage.

Agile and Stealthy. The serpent can take the Hide action as a bonus action.

Sseth’s Will. The serpent obeys only commands given by Yuan-Ti and is compelled to protect them at all costs. If ordered to take actions that harm or betray a Yuan-Ti, the serpent will refuse and attempt to escape instead.

Multiattack. The serpent makes two attacks: one with its bite and one with its constrict.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 3) piercing damage, and the target must succeed on a DC 13 Constitution saving throw or be poisoned for 1 minute. The poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Constrict. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage, and the target is grappled (escape DC 13). Until the grapple ends, the target is restrained, and the serpent can't constrict another target.

Defensive Coil (Recharge 5-6). When the serpent is hit by an attack, it can use its reaction to coil around itself, gaining a +2 bonus to AC until the start of its next turn. The serpent can only use this feature once per short or long rest.