Echo Knight of the Concrete Jungle

In life, Sergeant Dean Robinson was a soldier. After being slain by a fallen angel in a designer suit, he's drafted into a cosmic war. Resurrected with a divine 'System' interface only he can see, Dean becomes an Echo Knight, Heaven's last-ditch effort to save Earth. Guided by a stoic, beautiful Seraphim, he must battle monstrous giants and demonic forces on the streets of Boston. But his greatest weapon might be the very darkness the enemy injected into his soul, a corruption that could save humanity or damn him forever.