If at Faust You Don't Succeed — Roger Zelazny; Robert Sheckley

The last Millennial contest--between the forces of Good and Evil for control of the universe--didn't work out quite so well for Evil and its rooters. But it's time for the next round, and this time the demon Mephistopheles is carrying the ball for the forces of Darkness.

But all is not as it seems. The harried archdemon mistakenly signs up a medical cutpurse named Mack the Club, thinking him the learned Dr. Faust. The demon Azzic, still stinging from Evil's last defeat (and not being chosen to head the current effort), takes events into his own claws. And the pious angel Michael--well, let's just say some of his tactics in the titanic struggle to come are not quite cricket....