Wyvern

A wyvern is a huge flying lizard with a long snout and a poisonous stinger in its tail. While only a distant cousin of true dragons, wyverns' tendency to hunt in packs makes them dangerous foes. A wyvern’s body is fifteen feet long, and dark brown to gray; half that length is tail. Its wingspan is about twenty feet.

Abilities

 * Senses: Darkvision.
 * Languages: Draconic
 * Multiattack: The wyvern can make 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: Wyverns can bite at a target with it's giant teeth
 * Claw: Wyverns can make a claw attack.
 * Stinger: The wyvern can make an attack with its tail, which can poison a target.

Known Wyverns
Vox Machina encountered several wyverns being ridden by bandits in "Skyward". In a humorous turn of events, one of the flying beasts was polymorphed into a harmless rabbit, and consequently plummeted thousands of feet into the Ozmit Sea below.

Wyverns were a common element of Thordak's forces, usually used as mounts by the lizardfolk that served him.

Vasselheim has a group of wyvern riders among its military forces.

In the final round, and last battle of the Victory Pit tournament during the Harvest Close Festival in Zadash, The Stubborn Stock faced off against and in an exhausted battle defeated a large 20-foot wyvern that had its wings purposefully carved and cut so as to prevent it from flying.

"Vecna, the Ascended" (1x114)
Zahra and Kashaw both rode wyverns to the Entropis during Vox Machina's battle against Vecna. The duo managed to help out a bit, with Zahra attacking the newly risen deity and Kashaw healing the wounded members of Vox Machina. However, Zahra, Kashaw, and their wyverns were soon targeted by one of Vecna's Hold Monster spells, paralyzing all four of them. They were last seen falling past the tower, down into the mist below and out of sight