First Aid. Someone can tend to a target's bite injury. The healer must make a Wisdom (Medicine) check once every hour. On a success, the target makes its Constitution saving throw with advantage.
Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 8 (1d8 + 4) piercing damage, plus 10 (3d6) poison damage. The target must make a DC 11 Constitution saving throw or become poisoned and incapacitated for 1d12 hours. A Large or larger creature has advantage on the save. The creature can repeat the saving throw every hour, ending the effect on itself on a success. A protection from poison spell neutralizes the conditions, and a lesser restoration spell or similar magic heals the injury.
Description
The fierce snake presented here describes various ill-tempered, irritable, extremely aggressive snakes. Their venom potency make them much more dangerous than the poisonous snakes described in the Monster Manual. Incapacitating symptoms include dizziness, drowsiness, headache, coughing or difficulty breathing, convulsions, nausea, and vomiting.
Design note: This creature was purposefully designed to be more lethal and challenging for player characters than its Challenge Rating would suggest. With debilitating effects that can last for hours, it isn't tuned balance-wise for the Wild Shape feature or spells such as polymorph. A DM should consider excluding this creature as an option for shapechanging abilities or allow a relevant saving throw to be repeated at the end of each turn to end the poisonous effects.