What is one literary device that an author can use to create suspence or tension?

An author can utilise devices as short syntax. This creates a mode, as if the character can only comprehend their situation in short impulses. This creates tension because the full-stop establishes a pause between each sentence, so when read it sounds daunting. This can be further emphasised through tortured syntax - this shows breaks between thinking and action.

They can also use sensory language - words that relate to how the person is feeling - physically, mentally, emotionally etc. This shows that there is both a phycological and physical impact on the character caused by their situation.

Repetition is a great technique because it establishes a platform to build upon tense subjects - especially the repetition of loaded nouns and adverbs. Loaded nouns and adverbs carry strong connotations and allow the reader to be strongly engaged with the authors intentions. For example, the phrase such as 'dawned upon' weighs heavily on the word 'dawned' this is because we associate that word with a negative epiphany.

I hope this helps a bit!