I'm not entirely sure what 'I horn' specifically refers to in the context of Star Wars novels. There are many great Star Wars novels like 'Heir to the Empire' by Timothy Zahn which is very popular and set in the post - original trilogy era.
Since 'I horn' is an unclear term, it's difficult to point out a particular Star Wars novel directly related to it. However, the Star Wars Expanded Universe has a vast collection of novels. For example, 'Darth Bane: Path of Destruction' which tells the story of the origin of the 'Rule of Two' in the Sith order. Maybe if you clarify what 'I horn' means, it would be easier to recommend a relevant novel.