Misc. Author Notes: Back when this story was in the concept stage, I was toying with the idea of 'someone who could effortlessly defeat Gate of Babylon and/or Ionian Hetairoi, but
without being ridiculously OP in general' and came up with the idea of an attack that was otherwise weak but specifically targeted something based on age or how long ago they had passed on. Ideas changed as they go on, and it ended with Kara's Vanishing World - which rejects and destroys things that are supposed to have died or been destroyed already.
It's therefore worthwhile to note that Iskandar was always intended to be a Servant that Kara would face late in the Grail War, although the idea of pairing him specifically with Hakuno didn't come until way later.