What literary devices are used in the following lines from Twelfth Night? "Make me a willow cabin at your gate / And call upon my soul within the house, / Write loyal cantons of contemned love, / And sing them loud even in the dead of night; / Halloo your name to the reverberate hills, / And make the babbling gossip of the air / Cry out ’Olivia!’ O, you should not rest / Between the elements of air and earth / But you should pity me" (I.v.237–245).

The primary literary device that Cesario (who is Viola in disguise) uses is metaphor, mainly in extended form, or conceit. Cesario tells Olivia that he would stay near her and proclaim his love so that everyone would know about it. This is a metaphor, a comparison of unlike things for effect, in several ways. It becomes a conceit, an extended and generally complex use of a metaphor through a work.
The main metaphor is building a cabin near the outside of Viola’s estate, in which his soul will live. Cesario equates physical proximity—the cabin’s location—with emotional closeness—his soul inside the cabin. In addition, he mentions the natural world several times: through the use of “willow,” the “hills,” “the air,” and again, “air and earth.” In this way, Cesario is saying that his love for Olivia is natural.
Several times, he mentions proclaiming his love, both in writing and orally. While most of these are literal, as things that a man would actually do, he changes up the mention of the natural world and uses personification and metaphor to say that the air itself is spreading this information: “make the babbling gossip of the air/ Cry out . . . ” This reversal accentuates the idea that his love is natural, as the air itself is saying it; in turn, the air would convince her of his love because she would constantly hear of it—the physical manifestation, in this case sound, again equated with emotion.

Viola’s speech beginning “Make me a willow cabin at your gate” occurs in act 1, scene 5 of Twelfth Night. Viola, in disguise as Cesario, has been sent to woo the Lady Olivia on behalf of her new master, Duke Orsino. Viola delivers this monologue in response to Olivia’s question of what she would do if she were the one wooing, and Viola’s impassioned poetry lays the groundwork for Olivia’s misplaced infatuation with Cesario. The brief monologue, written in blank verse (un-rhymed iambic pentameter), employs many different literary devices to do so, the most ubiquitous of which is hyperbole. Throughout the monologue, Viola exaggerates her acts of love for poetic effect, saying she’d confine herself to “a willow cabin”—a small enclosure of willow trees—at the entrance of Olivia’s estate and sing out about her love so loudly that it would echo through the surrounding hills. The monologue also contains several instances of alliteration, first with “cantons”/“contemned” in the second line, then “Hallow”/”hills,” and finally “Olivia!”/”O.”
Ultimately, the monologue is an appeal to pathos, the literary device of using language and imagery to elicit sympathy as a tool to make a point or win an argument. When Viola ends the monologue with “But you should pity me!” it’s a direct plea that Olivia at least have some sympathy for her suitor’s heartache and desperation.