It sounds very much like the Eternal Wonder, the difference being the Eternal Wonder must reside within the Secret Realm, but the Supreme Technique is the mage's permanent skill.
If Dazzling Star has already constructed the Supreme Technique, she could overwhelm Ash simply by wearing him down. Conversely, if Ash has mastered the Supreme Technique, he can at least remain undefeated even if he cannot win.
So does Ash have the Supreme Technique?
Of course he does; Death Mad left many techniques.
But he lacks the Seven-winged Source Power.
