These monks favor grappling, suffocating and constricting opponents with expert abuse of joints, muscles, and bones, or taking lives from the inside with their various venomous strikes. Students who practice this art fall into three distinctions of mastery, Cobras, Vipers, and Boas.

A Cobra focuses on their poison tecniques and faith to the snake gods, who grant them their venom. A Viper focuses on speed and form, practicing the purest form of the martial art. A Boa focuses on their body, pure strength through mass with the experience to back it up.

All who follow the Way of the Serpent acknowledge the snake gods. Dendar, the Night Serpent. Mersshaulk or Zehir, Master of the Pit. Sseth, the Sibiliant Death. The distinctions each tend to favor one of the gods, Dendar for Vipers, Zehir for Cobras, and Sseth for Boas.

Whichever distinction they fall into, Monks who follow the Way of the Serpent are deadly assassins, hunters, and predators in their own right. You'll likely never see them, though, even if they're coming right for you.

Constrictor Kata

At 3rd level, your training in the way of snakes allows you to leverage both your own and your opponent's bodies through speed and precision. You gain the following benefits:

• When you attempt to grapple or maintain a grapple on a creature, you can use Dexterity (Acrobatics) in place of Strength (Athletics).
• You have no movement penalty while dragging a grappled creature.
• You have advantage on attacks against a creature you have grappled.
• To gain these benefits, you must have both hands (or legs or tail, as needed) free when you attempt and maintain the grapple.

You learn how to read, write, and speak Naga. If you already know Naga, you learn to read, write, and speak Draconic.

Merciless Fangs

At 3rd level, your observation of snakes has taught you to end things quickly, and without restraint. When you successfully grapple a creature, choose whether you do so with your legs, arms, or (if your race provides) a prehensile tail.

• Legs: Your movement speed falls to 0, and cannot be increased. However, when you take the attack action against the grappled creature on your turn, you can make an additional unarmed strike at the same target as part of the same action. Once per turn, you may choose to spend a ki point to do this again. You regain your movement speed when you release the grapple.
• Arms: You gain advantage on checks made to maintain the grapple, and deal poison damage equal to one roll of your martial arts die to the grappled creature at the start of each of your turns (no action required). Once per turn, you may spend a ki point on your turn (no action required) to deal this damage again.
• Tail: While you have a creature grappled with your tail, you may attempt to grapple another creature, but must use your arms.

Slithering Stalker

At 6th level, you further hone your understanding of the snake and how it hunts. You gain the following benefits:

• You gain expertise in Stealth or Sleight of Hand. You must first have proficiency in the skill you choose to gain expertise in.
• When you fail a Charisma (Intimidation) or Charisma (Deception) check, you may channel the essence of snakes to reroll it. Once this feature turns a failure into a success, it cannot be used again until after a long rest.
• You can spend 2 Ki points to mark a creature as prey and begin observing it, learning more about it the longer you do so, up to 8 hours. Only one creature can be marked at a time, marking another creature at the same time removes the mark from the first creature (not the effects gained in that time).
  • 1 minute of observation: You learn the target's highest Ability Score and what that score is.
  • 10 minutes: You have advantage on attempts to grapple the chosen target.
  • 1 hour: You may use the Ki effects of Merciless Fangs against the chosen target without spending Ki points. After the hour, the promise of a hunt stirs the snake inside of you. Make a WIS save against your Ki DC. If you fail, you are driven mad with hunger, and your sole intent is to kill the marked target. This madness only ends when the target is confirmed dead or you go unconscious. If you succeed, you suppress the urge and do not have to make this save for the next 24 hours.
  • 8 hours: You are rewarded for stalking your prey. You have advantage on all Charisma checks and saves against the target.
  • These effects last for 1 week, and you may release the mark on the target (no action required) at any point.

Sleight of Hand

Gain expertise in Sleight of Hand.

Stealth

Gain expertise in Stealth.

Might of the Boa

At 11th level, you count as 1 size larger for the purpose of grappling. Additionally, you gain the ability to throw a grappled creature as an attack action. This takes the place of your entire attack action, but allows follow up from Martial Arts, Flurry of Blows, etc. The creature attempts to escape the grapple. If you win the contest, the grappled creature is thrown 10 feet in any direction and lands prone. If not, the creature escapes the grapple.

Apex Aspect

At 17th level, the snake gods acknowledge your dedication and prowess, and answer your calls for strength. As a bonus action, you can spend 6 Ki points to become an aspect of the snake gods for 10 minutes. You maintain this form until you go unconscious, die, or end it early as a bonus action. While in this form, you gain the following benefits.

• You become surrounded in magical scales, like a second skin. You have resistance to non-magical bludgeoning, piercing, and slashing damage, immunity to poison damage and the poisoned condition, and +1 AC.
• All unarmed strikes and attacks with your Bite deal additional poison damage equal to your WIS modifier.
• Your head is surrounded in glowing green energy, creating a serpentine visage. You gain a Bite attack, which counts as a natural weapon for you. It uses WIS for attack and damage rolls, and deals 2 martial arts die poison or magical piercing damage (you choose).
• You heal for half of all poison damage you deal, rounded down.
• You can spend 1 ki point on a hit to try to severely poison the target. The enemy creature must make a CON save or take poison damage equal to your WIS mod and be poisoned for the next minute.