CODA

concluding section of a musical or literary composition

something that rounds out; summarizes or concludes

SYN - finale

"He had built up such a massive piece of work, now all that was needed was to attach a coda and it would be complete."

"The first 400 pages of the book where entertaining and insightful, but it wasn't until you had finished that you realized all 400 pages were in preparation for the magnificent coda."

"He had only looked at the coda and thus had not understood the process of reasoning and many important details that leads one to such a conclusion."