The wyvern's armor doesn't protect its neck, attacks against it gain +5 to hit.
Multiattack. The wyvern makes two attacks: one with its bite and one with its stinger. While flying, it can use its claws in place of one other attack.
Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 11 (2d6 + 4) piercing damage.
Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) slashing damage.
Stinger. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 11 (2d6 + 4) piercing damage. The target must make a DC 15 Constitution saving throw, taking 24 (7d6) poison damage on a failed save, or half as much damage on a successful one.
The wyvern can take one legendary action per round.
Wing Attack: Adjacent creatures make a DC 15 strength saving throw, on a miss they are pushed back 10 feet and land prone.
Description
Cousins to the great dragons, wyverns have two scaly legs, leathery wings, and a sinewy tail topped with a poison stinger that can kill a creature in seconds. This one wears armor.