AS SPYRO,ENTER NASTY KNORK'S LAIR. TALK TO FLAME. HIT HIM WITH A FIRE BOMB. HE WILL BOUNCE UP AND DOWN. GO BACK OUTSIDE TO DRAGON VILLAGE. GO BACK IN THE TUNNEL. TALK TO HIM FOR HIS SECOND PHRASE. HIT HIM AGAIN AND GO BACK OUT. COME BACK IN AND TALK TO HIM. HIT HIM WITH ANOTHER FIRE BOMB. HE SHOULD START RUNNING!
Once you beat the boss in a realm go back to the main area (where the moneybags depot is). Start charging and then when your still holding X press A. For a short period of time the sky will change colors.
P.S. I haven't tried this in volcanic isle or lost cities but I'm 100% sure it works in dragon village and 95% it works in icy wilderness.
Alternate Ending - Collect all the Dark Gems, Light Gems, and Dragon Eggs