Someone already posted a similiar thing however the ogre lavaburst in ring of conquest is affected by gcd and the location is a bit crap.
1. Be alliance
2. Play death knight
3. Get 'Sigil of Dark Simulacrum' the item that enhances your dark sim ability in Ashran
4. Go to the Emberfall Tower at the Horde base and dark sim Jeron Emberfall's Fireball spell.
5. You now have a spell that does 100k damage with -NO GLOBAL COOLDOWN-
6. Solo the Ashran battle and singlehandedly kill the horde boss in seconds.
I already discovered this bug on the beta but since posting beta exploits is not allowed here I waited until it went live like this. Here is the video, don't forget to watch the 2:40-2:50 part
https://www.youtube.com/watch?v=UIWXbT-XiW0