Edgar Allan Poe's "The Raven" is one of great balance and rhythm; it is noted for its melodic qualities in its rhyming trochaic octameter.  Stanza 12 of this poem certainly exemplifies the beauty of Poe's poem. In it there are several literary devices employed:

Allusion

Poe makes reference to the bust of Pallus, the bust of Athena, the godess of wisdom.  Also, he refers to the raven as "this ominous bird of yore"; the raven has been historically connected to magic, having been associated with witches and warlocks.  The Celts believed that the goddesses of war called the ravens to feast upon the dead in battlefields.  And, Native Americans associated the raven with death, as well, perceiving it as a symbol of the transition into the afterlife.

Parallelism

Poe's poem is replete with parallelism.  For instance, in each line, Poe makes use of participles lending rhythm to the lines.  In this stanza, the first and third lines are parallel in sentence structure.

Imagery

The fifth line contains images of death:  "grim, ungainly, gaunt, and ominous bird of yore."

Anaphora

The repetition of the first set of words, or anaphora, is used in the first line of Stanza 12 as "But the Raven" is repeated from Stanza 10.

Assonance

The repetition of vowel sounds followed by different cosonant sounds, occurs in the first line of Stanza 12:  "sad fancy" as the /a/ sound is repeated with different cosonants, /s/ and /f/

In the fourth line, "ominous bird of yore-- has the /o/ repeated with different cosomants.