Q: Hack?

Ok so, there is this GODLIKE Night Elf Priest (Of course she can kill me easily, being Alliance, lol.) who keeps squatting me like a fly.
Im using a lvl 65 Mage, lvling up in Blade's Edge, and this lvl 67 Shadow Priest named Lanaleya always manages to kill me somehow.
I have lost fair and square, and for that I am not mad, but she can kill me while she is on her MOUNT.
Yes, you read that right, while she is on her mount, she can cast 3 spells at a time, leaving me with damage over time debuffs that kill me miles away from the terrain.
Yes, I did get away from any high structures. And while I was typing, this little ***** killed me again.
Is she hacking? should I try and film this?

More likely that he's dismounting, casting levitate, and casting whatever DoTs on you while he floats slowly downwards.