User blog comment:B214/Question and Answers 2/@comment-86.81.216.93-20140529172958/@comment-1359322-20140529234700

^^This.

Euclid only uses his Demonic Power to enhance his Boosted Gear. Also, Demonic Power can return, it's like Issei sacrifices his stamina to use the CCQ, the stamina doesn't disappear, it just becomes empty once used finish and would return later.