Urban Gladiator by Anya Summers

Four times a year, a witch is chosen.
Four times a year, a witch is left bound in a clearing –
Served up as a sacrifice to honor the peace treaty.
But those offered up in tribute never return.

The rulers of Avalon exact vengeance on my people.
But many forget they started the war.
They are monsters. They are murderers.

And now it’s my turn. I volunteered to save my sister.
Only I wind up belonging to him.
He’s the heir to the throne, and my vilest enemy.
He’s bent on making me his slave both in and out of bed.

But this witch will never surrender.