Bride of Death (Marla Mason Series #7)

Marla Mason has been a mercenary, chief sorcerer and protector of a city, and an occult detective, and now she's a goddess of Death... but only part-time. She gets to spend six months a year walking the Earth as a mortal, and she's chosen to spend that time fighting monsters for fun and personal redemption. Armed with axe and dagger, with the living severed head of her worst enemy in a birdcage for a traveling companion, she sets out on a motorcycle on a journey of self-improvement and other-destruction.