Who committed more moral atrocities in the OT God or the Devil?

God did deliver the Israelites from their captors. That involved heartache, but they had been duly warned. God lets people make their own choices but people have to accept the consequences. When one nation enslaves another, the price is war and that is ugly. In this particular case, God waged the war after several warnings and opportunities to change and let the Israelites go free.