We currently don't have a really good framework to addess per-map champion balancing. There's a lot of design organizational talks behind-the-scenes to figure out how best to do this sort of stuff. It won't happen overnight, but we do know that some champs are horribly unbalanced on certain maps, and we're not OK with it.
Like for Darius I would have his ult scale with number players in area like wukongs passive.
And for assassins and adc's I would have item(s) that scale with level and reverse scale with health, the more health you have, the less damage and/or movement speed you get(level scaling is so that rushing it wont give absurd stats). Call it "Will of the night stalker". Make it build from a zeal and brutalizer.
Thanks for the update regardless.