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Large dragon, unaligned
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.
Sting. 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.
Travelers in the wild sometimes look to the skies to see the dark-winged shape of a wyvern carrying its prey. These cousins to the great dragons hunt the same tangled forests and caverns as their kin. Their appearance sends ripples of alarm through the borderlands of civilization.
Aerial Hunters. A wyvern doesn't fight on the ground unless it can't reach its prey by any other means, or if it has been fooled into a position from which aerial combat isn't an option. If forced into a confrontation on the ground, a wyvern crouches low, keeping its stinger poised above its head as it hisses and growls.
Aggressive and Reckless. A wyvern intent on its prey backs down only if it sustains serious injury, or if its prey eludes it long enough for another easier potential meal to wander along. If it corners a fleeing creature in an enclosure too small to enter, a wyvern guards where the quarry hides, lashing with its stinger whenever opportunity allows.
Tamed Wyverns. A wyvern can be tamed for use as a mount, but doing so presents a difficult and deadly challenge. Raising one as a hatchling offers the best results. However, a wyvern's violent temperament has cost the life of many a would-be master.