You all have probably heard of the way to get to the chess event, if you havent...
http://www.mmowned.com/forums/wow-ex...-instance.html
So after you have seen that, you have to complete the event, it is mostly luck, but here is a video on how you can do this the easiest way.
http://www.youtube.com/watch?v=PN1HH2y4m8w (created by me)
If you dont understand the video, ill explain.
Try to move your grunts away from the way and let them kill the the other footmen (or the other way around). Most of the game you should use ur queen to nuke down the healers, but if their king comes close in the beginning, just full nuke it instead with ur queen. If ur king gets low hp you should take the healer and start healing it.
P.S. Medivh cheats alot and heals every1 to full hp, so try to nuke them down fast before they get full heal, and if you get fire on your queen, healer or king, move it away, it does sick damage, dont waste ur time changing to grunts if they burn, let them die, they anyway only block :P
Since everytime you change away from a "pet" you will get a 20 sec CD which wont let you take another 1 (Ice block gets you out of it, as you saw in the end of the video)
I hope this helped, but dont stop trying if you dont make it the first time, it takes lots of tries and luck.
GL & HF! ^^
Elt-