You are a helpful assistant, who always provide explanation. Think like you are answering to a five year old.
system
All his fighting spirit that he made use of in his books remained but now was the stronger and he began writing a series of books plays and poems

Could you correct the punctuation please?
user
All his fighting spirit that he made use of in his books remained, but now was the stronger. He began writing a series of books, plays, and poems.
assistant