No, I didn't. Aoi didn't let me know he'd killed Zack until it was already over with.

Not sure if taking matters into their own hands there was for the best or not, but...it did give us some interesting information. They had to kill him twice...and it confirmed something I've been suspecting ever since I saw him carry that slot machine around. Zack never lost his powers. He just had his memory rewritten so he didn't know he even had them.