Also question is, why did Dean Fogg make a deal with the library?
Towards the end of season 13, we see Dean Fogg asking the library to give them more magic. He explained it at the end. His only duties is to the school and its students.
Also, what happened to Marina the magicians? MARINA! Well, Marina 23. See, in the current timeline, she's actually dead, because she ran afoul of the Beast when Julia was trying to defeat Reynard.
Secondly, how did Marina come back to life?
Having nowhere else to turn to, she returns to Julia to help her kill Reynard. A couple episodes later, Marina is brought back to life briefly with a necromancy spell casted by Julia and Kady, she provides relevant information about how to defeat Reynard before her time on earth expired.
What happens to Julia in the magicians?
Following complications in labor, Julia gives birth to a baby girl, who she names Hope Quentin. Julia and Penny eventually raise their child together as they set out to find their friends in the new Fillory.
