Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d4 + 8) piercing damage, and the target must make a DC 17 Constitution saving throw, taking 19 (6d6) acid damage on a failed save, or half as much damage on a successful one.

Spit acid. Ranged Weapon Attack: +7 to hit, range 40/80 ft., one target. Hit: 23 (6d6 +4) acid damage.

Corroding Touch (Recharge 5). The viper corrodes a nonmagical metal object it can touch. If the object isn't being worn or carried, the touch destroys a 5-foot cube of it. If the object is being worn or carried by a creature, the creature can make a DC 16 Dexterity saving throw to avoid the viper's touch.
If the object touched is either metal armor or a metal shield being worn or carried, its takes a permanent and cumulative -4 penalty to the AC it offers. Armor reduced to an AC of 10 or a Shield that drops to a +0 bonus is destroyed.
If the object touched is a held metal weapon, the weapon takes a permanent and cumulative -3 penalty to damage rolls. If its penalty drops to -6, the weapon is destroyed.