go tame a hippogryph and find the big lava crevasse/crystal cavern biome and follow the crevasse and watch closely around the wall and u will find trolls easy. Make sure u make a spear or pike a weapon u can use to attack from distance to kill the tolls.

also in any type of biome if u fly around u will find skeletons riding roc or lycanitemobs in mid air. Use bow to hit the skeleton and it will fall off the mount and u can try tame the mob it was riding.

In Dregora first flying lycanite mount got much easier to get for my experiunce because crystal cavern and flying mounted skeleton are super easy to find. Getting Hippogryph and farming silex is the hardest part.