I did this in an AV somewhat by accident on all four of my shaman.

You just need a slightly drawn out game and you need to play where there are a lot of alliance. I actually ended up in a long base turtle where I got to blow EM+TS a few times in a group of about 10-15 alliance-- that certainly helped.

I think I ended up with over 370,000 damage on my lead and 340k on the rest.