I decided to kill Hannag but she was too tough (at level 11) so I ran away.

Now when I return to Cloisterwood I get immediately killed by her.

She is level 13 and I'm 16 so why? How does she kill me on her first turn?

I can't tell as I'm playing Honor and it just says "Game Over" but I don't know why. What did she kill me with?