In most of his short stories, Poe tends to rely on similar literary, or style, elements in order to accomplish common goals in his writing. As the grandfather of horror in American literature, and as one whose name seems to by synonymous with Gothic, Poe's literary style is most often meant to create tones of fear, mystery, and suspense.
"The Cask of Amontillado" is no different. The most prominent literary devices used in this short story which accomplish exactly this are point-of-view and atmosphere.
The story is told in first person point-of-view, which is very typical of Poe. He does this for several reasons. First, the narrator is not meant to be trusted. In many of Poe's short stories, the narrator is presented as mentally or psychologically unstable, possibly crazy (a very Gothic element). Montresor, the narrator of this story, reveals from the very beginning his intended revenge on Fortunado. He then recalls events with a lack of emotion, even voice, and almost a mirth at his circumstances. Such a narrator could be considered controlling but very potentially unstable, and should not be trusted. This narrator heightens the tones of suspense and horror, because the details of his crime are not compatible with his sense of calm acceptance.
Atmosphere, in any story, is the combination of setting and tone. Again, Poe is a master of creating horrific atmosphere in his stories. In this story, the specific place and time of the setting are intentionally left ambiguous. All the reader can do is interpret the many details suggesting the combination of Spanish wine, Italian and French characters, and a Scottish motto. If nothing else, the place is considered "far away," and foreign. Additionally, the details of Montressors' "palazzo" are suggestive of a haunted house. It is filled with Gothic architectural details, such as high archways, numerous large rooms, a long and dimly lit staircase down to the catacombs, moss and moisture. Such details of setting again present murky, dark, and mysterious tones, which heighten the sense of horror in the story.