You know, I never could understand why Nasu limited himself in such a way with the Assassin character-type. "It can't be anybody but one of the incarnations of Hassan"? What kind of crap is that!? He comes from freaking Japan, with all of it's legends about ninja, and he limits himself to just the Hassan clan? At least we had Fake Assassin and Fate/Extra Assassin to break up the monotony (not that I could find any fanart of Fate/Extra Assassin to save my life)!
OmniGman said: You know, I never could understand why Nasu limited himself in such a way with the Assassin character-type. "It can't be anybody but one of the incarnations of Hassan"?
He didn't limit himself. The corruption of the grail allowed for the fake assassins to be summoned.