This may have been discussed somewhere, but I just finished the book and had a major epiphany. This is written with no regard for spoilers. I know that can never be spammed enough, so read on at your own risk. The puzzel pieces Humans came to Roshar as the Voidbringers (probably through shadesmar) I think they came through and built Urithiru to use in conquering Roshar. Odium is captured somehow Great spirits can be captured in fabrials. Urithiru is a giant fabrial that they don’t understand. I think Odium is trapped in Urithiru. Our Radiants have steadily been manipulated by all three gods towards Urithiru. I think Odium wants them to free him while Honor wanted them to defend the prison. The Unmade lured Shallan the the heart of Urithiru, Renarin’s curupted Spren keeps dropping hints on how the place works. I think they will unintentionally free Odium. Odium is collecting Honorblades and Oathgates. This is how he will be set free. The oath pact is connected to the oathgates, which are activated by blades. I think if all the Honerblades are used on all gates it will set him free. To defend from this Honor(who knew his heralds were failing) convinced the Spren of some of the gates to never activate again. They basically say this to Shallan in Shadesmar. This also explains Odiums tactics. He wanted to prevent the Radients from connecting the dots on fabrial traps. He captures gates, but doesn’t use them. I think there is more here. I wouldn’t be surprised if there is some mistborn style manipulation of history going on by odium as well. Anyway, let me know what you think. Or, criticize my spelling and grammar. Whatever floats your boat.