In the last poster on this page we see Harry Potter and Voldemort facing each other against a foggy blue background. There's a flame-like red and orange texture at the bottom and between the two characters is the Elder wand. The only visible text on the poster is "IT ALL ENDS 7.15".
I think there are some important design choices made here, specifically relating to the text. It does not say the movie title, I believe this is because this is the poster for the 8th movie in the Harry Potter franchise, which is in reality an extension/pt. 2 of the 7th movie. So it's aimed towards people who have seen the other movies and recognize the characters on the poster. We can deduce that there will be a fight based on the intense stare-down on the poster. The wand dividing them not only shows the 2 divided sides,but also the end goal, to have that object in the end. The blue foggy background gives an intense feeling and mixed with the orange, it gives the overall idea of action (action movies tend to have orange/red and teal/blue backgrounds both on the cover and within the movies themselves. Furthermore, red \/orange and blue are not quite opposite on the color wheel but far enough from each other to create a striking contrast, adding to the idea of opposite sides and a "good vs. evil" battle.
When looking at the two characters on the poster we see they are both dirty and bloodied, suggesting violence and struggle.
The text "IT ALL ENDS" suggests that this is the end , the last movie, the final battle. We see who will come out the victor.
The poster is simple and almost minimalist but shows an aura of intensity and emotion.