The idiom "骄兵必败" is formed by sequentially combining four characters: "骄" (arrogant), "兵" (soldiers), "必" (inevitably), and "败" (defeated). The first two characters "骄兵" constitute a subject noun phrase meaning "arrogant soldiers", while the last two "必败" form a predicate verb phrase meaning "will inevitably be defeated". This direct juxtaposition creates a complete declarative sentence stating that arrogant soldiers are certain to be defeated, with no additional grammatical markers needed.