tips on no casualty run on impossible difficulty

[BB Shockwave]

Yeah, it's very unlikely you get Resurrect in Darion. My first game, I didn't get it until the Elven islands. In my second, I got it on the Islands of Freedom (the eldest Cook brother sold it).

Generally though, I think you have a chance to get either sacrifice or Resurrect on the Freedom islands. In my first game, pretty much every second Pirate there was selling Sacrifice.