We have decided that Corwin is old enough to read the Amber series because he is named after the main character. He’s reading it out of a large omnibus but I found a couple of copies of the original paperbacks, which have wonderful blurbs on the back. Corwin was particularly taken with the text from The Hand of Oberon which reads in part ” … lead by the super human Lord Corwin …”. For some reason that appealed to him.