There is a terrain exploit that allows players to stand on a group of stones hovering over the small waterfall located by the platform in Nighthaven and shoot other players without aggroing the guards.
Get on the stones and wait for members of the opposing faction to get on the platform (the main attraction of the whole event) and start raining hell on everyone.
This is especially useful for warlocks/mages because you can AoE a ton of people at once.