Hail a griffon tamer at any of the towers in Nektulos Forest. They will want you to find a griffon egg near N'Marr's Ascent (-435, -1403) or near Bone Lake. The griffon eggs are ground spawns call "a clutch of griffon eggs" and spawn at random locations relative to the above areas. They are harvestable nodes.
Reported loc's include:
Once you find and harvest one, you have 5 minutes to take the egg back to a griffon tamer for the reward, the ability to fly between the available towers in Nektulos Forest.