The phrase flocks of shadow (line 15) is an example of

Antithesis involves contrasting ideas presented in a balanced manner, highlighting the differences between them. The phrase "flocks of shadow" does not juxtapose opposing concepts; instead, it unifies the imagery of 'flocks' with 'shadow' to convey a singular, vivid idea.

Hyperbole is an exaggerated statement meant to create emphasis or effect. While "flocks of shadow" is evocative, it does not exaggerate to the extent typically associated with hyperbole. Instead, it employs a metaphorical comparison without the intent of overstatement.

Synecdoche is a figure of speech in which a part represents the whole or vice versa. In "flocks of shadow," there is no part-whole relationship; rather, shadows are being described in terms of flocks, creating a metaphorical image rather than representing a component of a larger entity.