The makers of the film spent over a year perfecting the design of the Sandworm to make sure it looked as intimidating and prehistoric as possible. They succeeded.
A blink-and-youll-miss-it scene in the trailer shows Baron Harkonnens elephantine form emerging from what looks like a bath of crude oil. It lasts only a second or two but it leaves a powerful impression.
The previews are quick to show House Harkonnen's complete contempt for humanity: burning trees, smoldering corpse piles and cluster bombs unleashed on helpless Fremen.
In the Harkonnen throne room, there's a six-legged black...thing which looks like it escaped from one of H.R. Giger's daydreams, which seems to be kept as a pet by the Baron or Piter. The Harkonnen servants—who are all bald and eerily thin, with white skin and solid black eyes—also look distinctly alien.
The Harkonnen army utterly demolishes the Atreides forces, with the help of a traitorous Doctor Yueh and 3 battalions of Sardaukar soldiers. The Sardaukar are also especially unsettling here, given that they prepare for battle by having their foreheads marked with blood, with a shot of the many people sacrificed for this goal.