User blog comment:Water Dragon Slayer/DREAM BATTLE CHRONICLES: SECOND MATCH!/@comment-4829046-20130723104110/@comment-7418318-20130723161316

But any spell would dissipate over time unless there is something fueling it.

Maybe she too got a demon heart locked away in the celler and Precht got the idea to get one for himself when he first saw it when he became the second master.

Or maybe the heart of some other highly magical being or even a magical being as a whole, though it would be quite cruel to have a living being locked away and abused as a power source for more than a hundred years.