Wicked Queen by Emma Dean

Death is only the beginning.
Odin has spent thousands of years moving pieces across the board to prepare for the day a blood witch is born who will be his downfall. Mika Marshall may be the last blood witch, but she isn’t sure she has the magic or strength to take down a god who’s been stealing power for longer than the devil’s been alive.
The Morrigan has made Mika into her heir, and while the future may not be clear, one thing is for sure, she is the only one with the skillset required to take Odin apart and destroy him…if she can get close enough to make him bleed.
Will Mika be able to fulfill the prophecy, or will the apocalypse they’ve all been trying so hard to prevent finally sink the earth into hell?