The Arena Man by Steve Englehart
As this is the 4th book in the series, I'm giving the synopsis for book one, The Point Man.
Max August was a point man when he served during the Vietnam War, the guy who had to lead his patrol through dangers he couldn't possibly anticipate. Now he's a disc jockey, at one with the music and his faithful audience . . . until the day when he is swept into a battle invisible to all but the participants.
For nearly five centuries, Cornelius Agrippa has fought against an evil that has threatened to corrupt and destroy everything good and untainted in the world. Now, Max has joined the battle. It wasn't his idea to fight a demonic entity that can become anything it wants: an undying monster or the most desirable woman in the world. Max has been chosen by fate to fight those who would use magick to destroy freedom and wreak havoc on an unsuspecting world. Along with Agrippa and Valerie Drake, a beautiful, talented singer, Max is the only hope of the free world.Kalimpura by Jay Lake
Third book in the series that started with Green, I'll give it's synopsis here, to avoid spoilers.
Her exquisite beauty and brilliant mind were not enough to free her from captivity. That took her skills with a knife, plus the power of a goddess.
She was born in poverty, in a dusty village under the equatorial sun. She does not remember her mother, she does not remember her own name--her earliest clear memory is of the day her father sold her to the tall pale man. In the Court of the Pomegranate Tree, where she was taught the ways of a courtesan…and the skills of an assassin…she was named Emerald, the precious jewel of the Undying Duke's collection of beauties. She calls herself Green.
The world she inhabits is one of political power and magic, where Gods meddle in the affairs of mortals. At the center of it is the immortal Duke's city of Copper Downs, which controls all the trade on the Storm Sea. Green has made many enemies, and some secret friends, and she has become a very dangerous woman indeed.
Dust City by Rober Paul Weston
With his dad doing time for the double murder of Little Red Riding Hood and her grandmother, Henry Whelp tries to keep a low profile in Dust City-a gritty metropolis known for its black-market, mind-altering fairydust. But when he begins to suspect that his father may have been framed, Henry ventures deep into the City's underworld. There he comes face to snout with the legendary mobster Skinner and discovers what really happened to his father... as well as the horrifying truth about fairydust.
Imager's Battalion by L. E. Modesitt, Jr.
The seventh book in this series, I'll give the synopsis to Imager, the first.
Although Rhennthyl is the son of a leading wool merchant, he has spent years becoming a journeyman painter. With his skill and diligence, Rhenn stands to be considered for the status of master artisan. Then, his entire life is transformed when his master patron is killed in a flash fire, and Rhenn discovers he is an imager-one of the few in the entire world who can visualize things and make them real.
He must leave his family and join the Collegium of Imagisle. Imagers live separately from the rest of society because of their abilities (they can do accidental magic even while asleep), and because they are both feared and vulnerable. In this new life, Rhenn discovers that all too many of the "truths" he knew were nothing of the sort. Every day brings a new threat to his life.