You have survived the first test, crawled out of the--metaphorical or quite literal--pit of snakes, and are now a Monk following the Way of the Snake. You lie in wait, intimidate, and strike like a snake, invoking the cold and calculating violence of the serpent. Whether you give your foes the ever-contracting suffocation of a python, a dose of the cobra's venom, or the sudden bite of the viper, you and the snake are one.

Serpent Style

Starting when you choose this tradition at 3rd level, you can invoke your studies of the snake when harnessing your ki. At the start of your turn, you choose which snake you emulate in your stance. Whenever you hit a creature with one of the attacks granted by your Flurry of Blows, you can implement the effect of your stance:

Python Stance. You flex and tighten your muscles, making yourself larger. The target must succeed on a Strength saving throw or be grappled. Targets you grapple in this way contest your Ki save DC, rather than a contested Strength (Athletics) check. While you have a target grappled in this way, you cannot make weapon attacks, but if you make further unarmed strikes against that creature, though they are not made with advantage, they deal an additional amount of bludgeoning damage equal to your Wisdom modifier. You cannot grapple creatures of size categories two sizes larger than your own: if you are a Medium creature, you can grapple Large creatures, but not Huge or larger. If you are grappling a creature with Python Stance and you change Stances, your grapple is resolved under the normal rules of a contested Strength (Athletics) or Dexterity (Acrobatics) check, rather than against your Ki Save DC.

Cobra Stance. You harness the power of venom, turning your body into a deadlier weapon. On a hit, you push poison through your limbs and into the target. This strike deals poison damage instead of bludgeoning damage. The creature must make a Constitution saving throw. If it fails, you deal an additional unarmed strike damage die of poison damage and the creature is poisoned until the end of your next turn. On a success, the creature takes none of the additional damage and is not poisoned.

Viper Stance. Your breath quickens and rattles. You can immediately make one additional unarmed strike against the same target. This additional strike is not considered part of your Flurry of Blows and deals piercing damage equal to a roll of your Martial Arts die instead of bludgeoning damage, and with no additional bonuses. If you hit, the target must make a Wisdom saving throw against your Ki save DC or be frightened of you until the end of your next turn.

Serpent's Student

At 6th level, you gain the ability to make yourself more like the snake. As a bonus action, you can gain one of the following effects, determined by your current stance.

Constricting Python. Until the end of your next turn, creatures you grapple have disadvantage on checks made to escape, and when you roll Martial Arts damage against a creature you are grappling with your Python Stance, you may reroll ones.

Vindictive Cobra. Until the end of your next turn, your unarmed strikes deal an additional Martial Arts damage die, which is poison damage. This additional poison damage is not doubled on a critical hit.

Baleful Viper. Until the end of your next turn, roll 1d20 when you make an attack during your normal action, Flurry of Blows, or reaction, and whether you hit or miss. If you roll a 15 or higher, you follow the attack immediately with an unarmed strike against the same target. These special unarmed strikes cannot deal critical damage or bonus damage, only piercing damage equal to a roll of your Martial Arts die with no other bonuses, though an attack roll which would ordinarily be a critical hit is still an automatic hit. These attacks also cannot cascade into further attacks, they can only be made as quick strikes after normal attacks.

You may use your Serpent's Student feature a number of times per short or long rest equal to your Wisdom modifier.

Serpent's Fangs

Beginning at 11th level, you gain a special attack action, based on your current stance. For 3 ki points, you may use your action to use one of the following techniques rather than making a normal unarmed or weapon attack:

Suffocating Python Jab: You make one unarmed strike against the target's nose, throat, jaw, or chest. If you hit, the attack is a critical hit, and the target is restrained until the end of its next turn as it tries to regain its breath.

Paralyzing Cobra Strike: You make one unarmed strike against the target's arm, leg, eyes, or ears. If you hit, the attack is a critical hit and deals poison damage instead of bludgeoning damage, and is doubled. The target cannot use that part of its body until the end of its next turn. If you strike the eyes, it is blinded; if you strike the ears, it is deafened; if you strike the leg, its movement speed is halved and it has disadvantage on Dexterity saving throws; if you strike the arm, it cannot make more than one attack and it has disadvantage on Strength saving throws.

Disorienting Viper Bite: As an action, you make one unarmed strike against the target's head, eyes, or ears. If you hit, the attack is a critical hit and deals piercing damage instead of bludgeoning damage, and is doubled. The target has disadvantage on perception checks, investigation checks, and attack rolls until the end of its next turn, as it struggles to get its bearings.

Serpent's Guile

At 17th level, your study of the serpent has permanently altered you.

Python's Choke: When you grapple a creature while in Python Stance, it is also restrained and begins suffocating under normal rules, and every point of bludgeoning damage you deal to the affected creature while in this stance reduces the amount of time it can hold its breath by one second per point of damage.

Cobra's Acrimony: When you inflict the poisoned condition on a creature while you are in Cobra Stance, you have advantage on additional Cobra Stance attacks you make against that creature.

Viper's Rattle: When you take damage from a melee attack made within five feet of you while you are in Viper Stance, you may make a retaliatory unarmed strike without using your reaction. These attacks do not benefit from any other features.

Additionally, you can freely change your stance during your turn or when you make a reaction attack, though you cannot use this benefit to make more attacks than you are ordinarily capable of making.

When you roll initiative, you may expend 5 Ki Points to roll a Martial Arts die and add the result to your initiative roll. If you do so, for the duration of the combat, you have advantage on saving throws made to resist the frightened and poisoned conditions and checks and saving throws made to resist or escape the grappled condition, and you are immune to poison damage.