A book would hopefully have multiple protagonists and tell the story from many perspectives (preferably from the angle of each faction; Bandle City, Ionia, Bilgewater, Noxus, Demacia, etc.). Garen, Kat, Ashe, Trynd, and Trist would be good options for the main character of their respective factions, as they fit the role, but the protagonist role is interchangable. The champs affiliated with each faction would probably be supporting characters (Cass and Swain for Noxus, Lux and Xin for Demacia, Teemo and perhaps Veigar for Bandle City, etc.). The Void story would probably be covered as well, so Cho, Kog, Malz, and Kass would be the center of attention. Hopefully many of the independent champs (Fiddle, Morde, Vlad, etc.) would get their story covered as well, and many mysterious champs like Jax would have their secrets revealed.