Something like this has been posted before but it never showed a way for it to be utilized.
Step 1: Find someone who is an herbalist.
Step 2: Get that person to transform into an herb.
Step 3: Use the Potion of Illusion to transform into an herb.
Step 4: The person you found uses the Potion of Illusion on you so you are both moving herbs.
Step 5: Queue into the battleground and only accept the queue after you both are transformed into herbs then you will actually be herbs inside the BG.
Keep using the Potion of Illusion on each other ever minute and 30 seconds to always be in herb form and barely get hit because you blend in so well.
I won like 5 BGs in a row using this strat.
Also, if you pick up a flag in herb form, it will be invisible even if you fall out of the form. I'm not sure if this belongs in the exploit or guide section, but considering that the flag is invisible even out of herb form I'd say so. If not please let me know and I'll move it.