Werewyvern

The werewyvern doesn't provoke an Opportunity Attack action when it flies out of an enemy's reach.

The werewyvern makes three attacks, using Javelin or Rend in any combination. It can replace one of these attacks with one Stinger attack.

Melee or Ranged Attack Roll: +7, reach 5 ft. or range 30/120 ft. Hit: 18 (4d6 + 4) Piercing damage.

Melee Attack Roll: +7, reach 5 ft. Hit: 18 (4d6 + 4) Slashing damage.

Melee Attack Roll: +7, reach 5 ft. Hit: 7 (1d6 + 4) Piercing damage plus 16 (3d10) Poison damage, and the target has the Poisoned condition until the start of the werewyvern's next turn. If the target is a Humanoid, it is subjected to the following effect. Constitution Saving Throw: DC 16. Failure: The target is cursed. If the cursed target drops to 0 Hit Points, it instead becomes a Werewyvern under the DM's control and has 20 Hit Points. Success: The target is immune to this werewyvern's curse for 24 hours.

The werewyvern shape-shifts into a Medium wyvern-humanoid hybrid or a Large wyvern, or it returns to its true humanoid form. Its game statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed.