How do I get to the mini-boss in the Stone Wave Cliffs location?

[Azura]

In the farm location you have a large space where you solve a puzzle with Petanks, you can't go any further just on the ground because there's a fence ahead with some kind of root. Usually everyone goes around the side and goes on, but I noticed that down in the location behind this root there is a big mob and loot. I can't figure out how to get there, any ideas?