Final Crisis: Revelations

Crispus Allen used to be human, but since he was killed and bonded to the Spectre, he's been wreaking vengeance without justice or remorse in the name of God. When he's sent to do his duty with Libra, he finds himself unable to have any impact, and unable to touch or hurt the villain. Before he gets answers to his questions about that, he's sent after his next target, whom many would consider a hero.