Dune

Schemes within schemes within schemes. George R R Martin levels of specificity for descriptions of imaginary ecological systems. An amazing blend of lazily generated lore, soft magic, a central source of power (praise be blue eyes and spice), and an immensely complex political structure built around it.

What I love about Dune is the equilibrium of power that exists before the discovery of spice's true capacity for divination (which you'll see if you make it to Dune Messiah).

• Every surviving family has nuclear, so atomics have been dismissed as a long-outdated version of mutually assured destructions.
• Guns are largely irrelevant because of shields, which only permit slow-moving projectiles to penetrate. This means we're functionally back to the medieval ages of getting up nice and close to you poke someone with a sharp stick.
• Lasers are also largely irrelevant because of shields, because combining the two creates a nuclear blast instantly killing the instigator and defendant.
• On Dune itself, shields (and any human activity bar that of the Fremen) summon the scourge of the planet, the sandworms. Nature reclaims all.
  It's a brilliant way to escape the unbounded potential of soft-magic deus ex machinas in your story.

The power dynamics of the ending are interesting, because it's apparent that the next weapon of mass destruction (or mass anticipation) has been discovered. While the ending isn't as compelling as I'd like for this reason, it well-positions the world for the sequel.

But what I love even more is the implication that divination unlocks the next step of humanity.