Tension Devices

Pathetic fallacy

Ellipsis

Fiction hooks

Sentence Structure

Tripling

Repetition

Onomatopoeia

Metonymy of gloom and horror

Withholding information

Powerful adjectives

Show don’t tell

Red herrings

Changing perspectives

Changing pronouns to add mystery

Releasing tension with sarcasm to lull into false sense of security

Varied punctuation

Dropping clues

Alliteration

Changing mood

Cliff hangers

Interruptions in speech

Flashbacks

Short paragraphs

Non-linear narrative

Changing font/italics/bold

Imagery

Directly addressing the reader

Twists in the story

Rhetorical Questions

Stammering in speech