Mary Shelley uses several literary devices in her novel Frankenstein, such as imagery, foreshadowing, hyperboles, allusions, metaphors, similes, and others.
Foreshadowing is an important element of the novel. In fact, this is the main reason why the narrative is so thrilling and suspenseful. For example, at the very beginning of the story, when Victor and Walton meet, Walton tells Victor about his expedition and says:
One man's life or death were but a small price to pay for the acquirement of the knowledge which I sought, for the dominion I should acquire and transmit over the elemental foes of our race.
This actually foreshadows Victor's death, as he also loses his life in the pursuit of knowledge.
In the same chapter, Victor tells Walton his life story. He mentions his happy childhood and his family's decision to adopt Elizabeth, who will later become his fiancée. Shelley uses hyperbole to describe Elizabeth, in order to showcase how Victor perceives her:
"Everyone loved Elizabeth. The passionate and almost reverential attachment with which all regarded her."
Shelley also incorporates a lot of imagery into the narrative. For example, when Victor creates the creature and when it becomes alive, Shelley vividly describes Victor's thoughts, which helps the readers understand his mental and emotional state at that moment.
His limbs were in proportion, and I had selected his features as beautiful. Beautiful!—Great God! His yellow skin scarcely covered the work of muscles and arteries beneath; his hair was of a lustrous black, and flowing; his teeth of a pearly whiteness; but these luxuriances only formed a morehorrid contrast with his watery eyes, that seemed almost of the same colour as the dun white sockets in which they were set, his shrivelled complexion and straight black lips.
Throughout the book, Shelley uses a lot of allusions, metaphors and similes. For example, in Chapter VII, the creature says:
Like Adam, I was created apparently united by no link to any other being in existence; but his state was far different from mine in every other respect. He had come forth from the hands of God a perfect creature, happy and prosperous, guarded by the special care of his Creator; he was allowed to converse with, and acquire knowledge from beings of a superior nature: but I was wretched, helpless, and alone. Many times I considered Satan as the fitter emblem of my condition; for often, like him, when I viewed the bliss of my protectors, the bitter gall of envy rose within me.
The creature compares itself to Adam and even Satan, as Shelley incorporates a metaphor that includes biblical or religious allusions, as well as allusions to Milton's Paradise Lost.