Wyverns aren’t tamed by knocking out adults: find a nest, use a fast flyer with plenty of stamina, grab an egg, and escape quickly as nearby wyverns will aggro. Hatch the egg in a warm spot and raise the baby; this egg-theft-and-rearing process is the tame, and young wyverns have the unusual need for wyvern milk, which can be obtained from a knocked-out female or an alpha.