The Twilight Magus. The Sanford Files, #3

Exiled occultist Carl Sanford attempts to join a secret society as a stepping stone to even greater power while his old enemies hunt him across Spain in this new installment to the eldritch-rich horror pulp adventure world of Arkham Horror. Carl Sanford, once the Silver Twilight Lodge's great leader and now presumed dead, lives in anonymity in Spain, plotting revenge against those who betrayed him.
Alone, he calculates his first move to achieve power abroad is by being initiated into the mysterious ancient society called the Red Coterie to secretly take it over. Despite Sanford's reputation, the Red Coterie demands proof of his occult prowess, sending him on a quest to vanquish The Blood Moon, a reclusive blood magus manipulating humans and monsters alike to achieve their own ends. As Sanford uses every scrap of cunning he possesses to outwit his enemies and prove his worth, old foes from Arkham have discovered his existence and are coming to finish him off once and for all.