Answer:
Hoping for one less opponent at dawn, I watch the sky.
Step-by-step explanation:
The comma is used like that since the sentence is separated since it is a complex sentence.
Complex sentence contain one dependent and one independent sentence.
Dependent - Hoping for one less opponent at dawn
Independent - I watch the sky (I is the subject while watch is the verb)
Combine them with a comma to make,
"Hoping for one less opponent at dawn, I watch the sky."