ohai!
made a quick video for this because i got alot of people asking for it.
HOW TO:
1) Get to scholomance (in western plaguelands)
2) clear everything untill you get to some sort of class room (full with "Bored Students")
3) run to the table infront of the classroom next to the professor.
4) kill the professor and pick up Empty Polyformic Acid Vial
5) use the green vial on the table and you'll get the transformation
6) click on the vial to store the transformation for later use if you want.
NOTE: if you use it on another time, you'll get the disguise and a new empty vial. you can store this effect again, but next the next time you use it, it will be a shorter duration. eventually the vial will run out and you're left without a disguise.
2nd NOTE: This buff spreads in battleground. if you kill someone with this transformation, it will transfer to you! have fun in bgs with it ;D
This is probably a repost, but i made this thread for a full tutorial on how to do it. (Video and text style)