Case of the Burning Masks

Activated and triggered abilities are not themselves sources of damage. The source of an activated ability is the object whose ability was activated, and the source of a triggered ability (other than a delayed triggered ability) is the object whose ability triggered.

Being solved is not part of a permanent's copiable values. A permanent that becomes a copy of a solved Case is not solved. A solved Case that somehow becomes a copy of a different Case stays solved.

"To solve" abilities will check for their condition twice: once when the ability would trigger, and once when it resolves. If the condition isn't true at the beginning of your end step, the ability won't trigger at all. If the condition isn't true when the ability resolves, the Case won't become solved.