This requires a rogue, herbalism & a Blood Scythe (allows you to recieve Bloodvine), you will also need to be in a raid but preferably not leader (for resetting).

In ZG there are 2 (yes only 2) herb nodes which have only 2 humanoids guarding them. The 1st is the hut directly to the left right after you enter, the second is the hut to the right after the second bridge, infront of Snake boss room. They do not always spawn, if they do not just reset the instance (described later). If a herb IS up in these location, its as simple as a sap and a blind to be able to pick the herb and possibly recieve a Bloodvine in this manner.

To reset ZG: Head towards the door, make sure you are not the leader, promoting someone else if neccesary. Leave party and zone out. Reinvite the person that was in your raid and zone in with yourself as leader. Just be sure you are not the leader when you leave raid to reset.

(I have a few more farming tricks but I am not going to flood the forum with them)