First, grab the maphack from here:
Path of Exile MaphackNext, head over to the act 2 Dread Thicket.
Not much is in this zone, except for the possibility of a Rare chest. It is at the end of the map as it winds around, and not always there. With the maphack, you can really easily see if it is there or not by the shape of the map.
Check out these 2 images:
(!empty($user->lang['ATTACHMENT'])) ? $user->lang['ATTACHMENT'] : ucwords(strtolower(str_replace('_', ' ', 'ATTACHMENT'))):
POE_NoChest.jpg
(!empty($user->lang['ATTACHMENT'])) ? $user->lang['ATTACHMENT'] : ucwords(strtolower(str_replace('_', ' ', 'ATTACHMENT'))):
POE_chest.jpg
As you can see in the second image.. how the zone is sorta square at the end.. that is the signature of a large rare chest just WAITING to be opened.
It takes about 3-4 instances before it will pop. So if you dont see it at first, exit the instance, ctrl-click on the door to the instance and select NEW instance. Then try try try again.
Great place to farm.