I was sitting to see if Black Dire was going to pop so I could dispatch him for my SHM's Epic piece when I get hit from behind by Equestrielle.
So I took off running toward GF zoneline when I realized the the nag was Dk Blue to my lvl 53 Ranger so being near the ZL I decided to see if she had followed me and there she was trying her best to hit me again. I figured what the heck and started hacking away and blasting her with my spells. Equestrielle got me down to 18% and I got her below 20% and she turned and started to stagger awy. I figure since she is runnning b4 I did that it would be my fight to win so I spell, spell, hack, slash and next thing I knew here legs were going out from under her and "You have killed Equestrielle, you gain experience." WOOHOO.
I looted the horn from her and left it in my guild bank for a bard to use.
Do not know how many total hit points she had but I do know I got hit more times than I wanted to for 401hp.