Secret Art: Dragon In A Pot was said to be a secret technique created in order to cook a cosmic dragon as huge and vast as a universe. Using the cosmos as the pot and the stars as the lid, it would then use divine fire to boil the ingredients placed inside it.
While Ainsworth possessed the secret art that accompanied it, which allowed him to invoke divine fire, he ultimately didn't use it. After all, his intentions were merely to trap Elyndra inside it without seriously injuring her.
Other methods he possessed were somewhat insufficient in dealing with the death rule imbued by Elyndra's Imperial Execution (SSS). Those methods that could, would undoubtedly eradicate her along with her death rule.
Using the Secret Art: Dragon In A Pot was the most convenient method he possessed aside from using his Negation superpower or Ultimate Freedom. However, those weren't as flashy since Elyndra already knew he possessed freedom-related abilities due to his main class.
