Bro if you have a good rhynio killing one should be a breeze. I killed one HEAD ON with my rhynio that has 16k health and 600% melee. I was landed in front of him and spammed attack while he hit me back. And i STILL WON. For a higher level i wouldnt suggest taking it head on as the damage output is worlds apart from a low level. It will take a good 20 minutes but you can kill it in the air with relative ease. Btw i also was using a primitive rhynio saddle so this victory was purely because of my rhynio’s stats and no outside stuff.