Your question refers to “major” literary techniques, and asks for a concentration on prose fiction. While “metaphor” and “imagery” may be part of the linguistic arsenal of poets and some fiction writers, they are not “major,” but merely smaller tools in a much larger technique. Foremost among prose “techniques” are narrative voice, the balance of the reality/imagination duality, language manipulation (metaphor is one part of this), and what might be called timeline management.
Narrative voice refers to who is “telling the story”--first-person narrator, omniscient narrator, unreliable narrator, etc. Reality/imagination refers to the degree of verisimilitude of the action—does is take place in the “real world” (for example, 19th century Paris as in Balzac’s Pere Goriot (imagery may be part of this” toolbox”), complete with cobblestone, porch stoops, shops, etc.) or in a world of imagination (as in Mary Shelley’s Frankenstein)? Language manipulation refers to the author’s language choice—are the dialogue and descriptions linguistically believable and taken from a normative vocabulary, as in Hemingway’s The Old Man and the Sea, or creative and self-conscious, as in Joyce’s Finnegan’s Wake? Timeline management refers to the author’s manipulation of the unfolding of the plot—normative and like real time, as in Grimm’s Fairytales, or jumping from present to past to future, as in Faulkner’s As I Lay Dying? Of course the examples given are gross oversimplifications, and there are endless variations on these four major techniques, but they serve to demonstrate the major categories of “tools” available to the prose writer.