It comes from Alexander (The Creator) Savage. Most likely A11S, given that they usually go in order like that. (Page 1 from A9, Page 2 from A10, etc).
SE doesn't have loot tables open to the public on the Lodestone, and noone's bothered to make a list of what drops from each turn of the new Alexander raids, so we haven't updated every item to show their source yet since we don't usually speculate on drops (only confirmed drops)