Ok when wintergrasp is about to start on my server there is normally people standing where the portal spawn. Alot of them have already made a raid group, and ready to go there.
But one time i was very bored and thought of good old AV when i made portals inside there to Silvermoon/Exodar. So i thought i would make one ontop of the wintergrasp portal when the NPC started to cast one.
So i've tried this a few times and most of the times like 15+ people get teleported there, i get alot of /w "Ihate u" after ofc, but its just for fun.
This can also work to help your faction get the Tenacity buff to get that acievement. ( Win with the buff)