Wyvern

Imperfect Flight. While bloodied, the wyverns fly speed is halved, and it can't gain altitude.

Multiattack. The wyvern attacks once with its bite and once 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 target. Hit: 13 (2d8 + 4) piercing damage.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 9 (2d4 + 4) slashing damage. If the wyvern is attacking from above the target is grappled by the wyvern (escape DC 15). While grappling a target in this way the wyverns Speed is reduced to 0 it can't use its claws to attack any other creature and it has advantage on attacks against the target.

Stinger. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 11 (2d6 + 4) piercing damage. The target makes a DC 15 Constitution saving throw taking 24 (7d6) poison damage on a failure or half damage on a success.