Use "magnum opus" in a sentence

1. these twenty-four hours—to create this magnum opus, is to make available to me (when I flitz into you) the wherewithal to escape from your head

2. This was his magnum opus, i

3. To cross the Rubicon was his Magnum Opus, the biggest undertaking of his life

4. It would be his magnum opus, his greatest symphony

5. Evidence, his magnum opus was called