Bite - Giant Poisonous Snake

Monster Manual - 5e, D&D Basic Rules

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 6 ( 1d4 + 4 ) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 10 ( 3d6 ) poison damage on a failed save, or half as much damage on a successful one.