OK OK so I have not finished Bands of Mourning or read any of the Stormlight Archive (what I know from stormlight is from my friend, @Prism, as well as poking around on the coppermind for this theory) but I think that Alcatraz was made part of the cosmere. In book 2 (The Scrivener's Bones) a lot of the magic system is revealed and the connection between them, but it was also heavily implied that the reason the magic system was in place was because the Incarna "fell victim to a terrible calamity" that they brought onto themselves through a lot of time and a lot of sciency-wiencey stuff. I think that this "calamity" was the shard Odium, somewhere between him arriving at Sel and going to Roshar. From what I got from @Prism, they may have pulled Odium through the Cognitive realm using the weird orb thing that he told me was from Secret History, or another way. I think that Odium tried to make a magic system like that of Autonomy, as it is implied that they are allied. The investiture was, however, broken, as many things from Odium are. I believe that Alcatraz the 1st somehow broke the investiture so that Odium was cast back into the Cosmere, but preserved the magic system. This may have been documented in the Ancient Language but, as there is only one known pair of Translators Lenses (Alcatraz's were destroyed) it may take a long time to find. Also, Odium may have been brought to the Alcatraz earth after he was on Roshar, as the Knights of Crystalia seem to have a form of Shardplate and Shardblades. I am not sure about this theory so if anyone knows anything about this please add to it.