Edit: my level 22 mage couldn't do the entire quest chain. My 80 obviously could. I don't know what the level requirement is to do the whole thing.
Spoilers below.
Non-spoilerish spoiler: pay good attention to the dialogue, they explain troll druids.

Spoiler:
You get an item that turns you into a troll for 1/2 hour every 4 hours - which makes me think you get an item that turns you into a gnome alli-side (I want to go check but I promised the guild I'd wait!!), which means I GET TO BE A GNOME HUNTER! GNOME SHADOW PRIEST! GNOMES SHAMMY!!!! I'm so happy right now.

My 22 mage did get to do the chain until the quest that gives the item, so at least she'll be able to be a troll from time to time, even if she won't have the achievement.