What are the main expressive techniques used in the poem Jinse?

In Jinse, the poet borrows a lot of allusions such as Zhuang Sheng's dream butterfly, cuckoo's crying blood, tears in the sea and smoke in fertile fields, and uses metaphor and imagination to transform his auditory feelings into visual images. By combining the fragments of images, he creates a hazy realm, thus conveying sincere, strong and profound thoughts with the help of visually perceptible poetic images.

Jinse is the representative work of Li Shangyin, a poet in the Tang Dynasty. Original text:

I want to know why my Jinse has fifty strings, and each string has a youthful interval.

Zhuangzi daydreaming, a saint, was bewitched by butterflies, and cuckoo crowed in the imperial spring.

Mermaids shed pearl-like tears on the moon-green sea, and the blue fields breathed their jade to the sun.

A moment that should last forever has come and gone before I know it.

Translation:

Jinse, why do you have fifty strings? Every string and paragraph reminds people of the year of Huang Jinhua. My heart is like Zhuangzi, confused by butterfly dreams; Another example is watching the emperor, turning the cuckoo into a cuckoo. Hai Ming Yue Ming, Jiao Ren's tears are pearls. Lantian is sunny and warm, and you can see good jade and good smoke. The feelings of joys, sorrows and sorrows cannot be recalled today, but they have been inadvertently long ago. Although it is difficult for readers to understand the ideological content of the poem Jinse, the poetic realm that can be used to wander easily comes to mind.