Sorcerous Fire (Harem of Sorcery #3)
Lana Ames

Rebecca is a practicing witch--and already literally fighting demons--so she isn't fazed when the mysterious Lady Periwinkle asks for her help with a demon problem of her own. Granted, the sex magic thing is a little more unusual, though intriguing. But when Rebecca starts binding her harem of men, she quickly finds that the situation isn't at all what was described...in so many dangerous, and smoldering hot, ways.