Zombie Snake

If damage reduces the snake to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the snake drops to 1 hit point instead.

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 1 piercing damage, and the target must make a DC 10 Constitution saving throw, taking 5 (2d4) poison damage on a failed save, or half as much damage on a successful one.