I found a weird thing in my pdf copy: glabrezu outrider doesn't have her mount stats described and encounter with her doesn't list a mount either, despite her tactics heavily implying mounted combat. Which is weird, because all other cavaliers and other companion classes in the books have their companions detailed and listed. Unless I'm missing something, this could be a bug or omission.
It's not like it's too hard to get a stats for her horse or other mount, it's just a little thing which marred my impression of this otherwise totally perfect book :( Demon Knights are such a cool group.