From publisher blurb:
This particular installment of Exotic Encounters focuses on the oft-overlooked wyvern. These unusual, dragon-like creatures are depicted as dragon’s lesser cousins in Pathfinder and similar roleplaying games, but historically, and in fantasy literature, could take on a wide variety of forms and functions. One of the most popular uses for wyverns is as stylish mounts, and greenscale wyverns, the first new wyvern presented in this book, are a special breed designed to serve as mounts, with long tails and a devastating tail sweep that takes out grounded foes en masse. By contrast, the spinetail wyvern is as undomesticated as they come, with great sharp spines growing out of its back and tail, it is even more brutish and prone to violence than the more common wyvern. Finally, the twintail wyvern is remarkable for its two tails, each of which has a stinger that delivers a different kind of poison, each of which is even more effective when combined with the other.