Roxy?

OK, so i remember more of this story. Roxy is a girl with short black hair and red tips. She's an assassin but was originally trained as a Master Thief. She is kidnapped by her old Guild, the thieves and taken to a weird dungeon where there is a ritual going on. She's transferred to King Arthur times where she meets the knights when she is dumped into a pit of blue flames. That's the beginning but during her time she finds that she has a guardian that is a God. Later on she sets off under the disguise of a priestess to assassinate the leaders of the Saxons with Gawain as her protector.

So anyone know the story I'm talking about? I got one review but it turned out that it was the wrong story. If anyone can help me please leave a review. It would be much appreciated. Thank you all.

Blessed Be,
~Sandra~