Consider Quran 8:44: "Recall when He MADE THEM APPEAR AS FEW in your eyes when you met them in the battle just as He LESSENED YOU IN THEIR EYES so that Allah might accomplish what had been decreed." Why does Allah need to deceive?

We read in 8:44 that Allah intervened in human affairs by using deception to help the Muslims win.  Why did he not just use his magical powers instead of deception to help the Muslims win?