The more I think about it, I really like Taravangian's ascension. All the elaborate Diagram planning just to save a city was a letdown. I was a disappointing that that appeared to be his endgame in Oathbringer. But this is great.
Yes, it made sense for Smart Taravangian when we were assuming that Rayse/Odium's goal was to wipe out humanity entirely, although we now know that wasn't the plan. I was certain that Taravangian's actual endgame would have to rely on his "stupid" self and not be so obvious, but I had no idea what that would look like. But it the end, it all fit together so perfectly.
To be honest, Rayse was quickly becoming the one of the weakest part of the series, so this works out. Harmony's letter mentioning the lack of distinction between the Vessel and the Shard was starting to solidify that to me, by implying Rayse was more or less completely under control of the Shard. He was starting to become too similar to Ruin.
Since the gradual insanity of Cognitive Shadows (which the Vessels are) is such a major theme in this book, it's making me wonder. Obviously this seems to be Kelsier's primary motivation and also a major part of the Heralds/Fused/Szeth on Roshar proper. But maybe this is also Cultivation's goal - sidestepping this issue by replacing the Vessels, letting them have more control over the Shard. Maybe even going as far as being involved in Tanavast's death? I'm also thinking of Autonomy, who as far as I understand seems to have split herself (themself?) across multiple avatars. And maybe that's a different solution that lets them exert more Autonomy over the Intent of the Shard itself.
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I definitely did not forget to put the 2020 GOTD Guru winner, azuarc in my sig!