Final answer:
Eteocles slew Polyneices during the final battle, causing him to be left without a proper burial.
Step-by-step explanation:
Who slew Polyneices during that final battle that caused him to be left without a proper burial?
In Sophocles' play Antigone, it is revealed that Eteocles was the one who slew Polyneices during the final battle. Polyneices attacked Thebes seeking revenge, but Eteocles defended the city, resulting in the death of his brother.
This caused Polyneices to be left without a proper burial, as per the edict issued by Creon, who ruled in Thebes. Creon decreed that Polyneices' body should remain unburied and exposed, becoming a feast for dogs and carrion crows.
It is important to note that Antigone, the sister of Polyneices, defied Creon's edict and resolved to bury her brother, which ultimately led to her own tragic demise.