Crotaliboa

Lingering Toxins. If a creature is affected by the Crotaliboa's combined "Venom" action when attacked with the "Fabled Fangs" action, the creature must follow the guidelines stated for the effects of the venom (stated in the Actions). After surviving the venom's effects, the creature that was previously envenomed will have to succeed on a DC 5 Constitution Saving Throw in order to perform the following actions for the remainder of the day (or until a long rest is taken): Attacking, Sprinting, Readying, Disengaging, and Dodging.

Varying Movements. The Crotaliboa can choose between the following locomotion styles to benefit from them in certain situations:

• Concertina: Increases the Crotaliboa's AC by 2 for 3 turns after it stops moving.
• Serpentine: Increases the Crotaliboa's speed by 15 ft. if swimming.
• Sidewinder: Increases the Crotaliboa's overall damage by 3 points after it stops moving.
• Rectilinear: Increases the Crotaliboa's current Hit Points by 2 for every turn it moves in this style.

Bite. Melee Weapon Attack: +1 to hit, reach 10 ft., 1 target. Hit: 7 (1d6 + 2) piercing damage. 

Fabled Fangs. Melee Weapon Attack: +2 to hit, reach 11 ft., 1 target. Hit: 9 (1d8 + 4) piercing damage (can be used in synchrony with the "Venom" action, to trigger the effects of the Crotaliboa's venom).   

Tail Swing. Melee Weapon Attack: +1 to hit, reach 16 ft., 4 targets. Hit: 12 (1d12 +2) bludgeoning damage. 

Defensive Position. The Crotaliboa can enter a position similar to that of a defensive Corn Snake, and all attack rolls against the Crotaliboa while it is in this stance will roll disadvantage. This effect only lasts for the duration at which the Crotaliboa is in this position, and it may only remain in this stance for 3 rounds.

Striking Position. The Crotaliboa can enter a position similar to that of a reared up Rattlesnake, and all attack-based rolls against other creatures while in this position will gain an additional 5 (1d4 + 3) points towards the end-roll. This effect only lasts for the duration at which the Crotaliboa is in this position, and it may only remain in this stance for 2 rounds.

Venom. When used along with the "Fabled Fangs" action, the Crotaliboa will inject a potent venom that will require the victimized creature to succeed on a DC 12 Constitution Saving Throw every turn it is envenomed. On a successful save, the creature is unaffected by the venom for that round, but will have to repeat the Saving Throw on its next turn after the round ends and the DC will be increased by 2 for each successful save. On a failed save, the envenomed creature will take 3 poison damage per turn for 3 rounds.