Lord demon

Roger Zelazny

The great wars between gods and demons began five millennia ago, and ended with the demons' crushing defeat and banishment from their homeland. The demon race would have surely perished in the empty dimension of their exile had they not found a secret conduit to a safe and hidden plane called Earth. Greatest among the demons was Kai Wren, Godslayer and Lord Demon, a master swordsman, and glassblower who can contain entire universes in bottles of his creation, a legendary warrior who once singlehandedly destroyed a god. But now, Kai Wren must seek vengeance for the murder of his devoted human servant, and he fears that this one death heralds the crumbling of a peace that has reigned for a thousand years.