Slay 5 Dragonflayer Handlers and Skeld Drakeson. If you manage to do so, return to an Ember Clutch Ancient in the Ember Clutch.
All things in nature seek a balance. It is only through the interference of those not in tune with that harmony that the balance is shifted.
You waste your efforts when you kill the whelps and drakes. The real culprits behind the expansion of these magically burning woods are the newly awakened vrykul and their master, Skeld Drakeson.
If it's blood on your hands that you seek, start with them. You will find their lair on the south side of the Ember Clutch.