I do remember some things, but the majority of the questions were about WoT.
He said that all of his own books take place in the same universe, but not on the same world per se. The overall magic system was based on the principle of investing, i.e. people and things are invested by magic. So for example in Mistborn, the metals themselves aren’t magical, but they become a vessel for the magic.
Also he said that the ways of magic are different. In Mistborn it’s genetic (or through ingesting atium, but he didn’t talk about that). In Warbreaker it has to do with gathering other people’s Breath, etc.
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