wait another 1/2 an hour and bring a hobgoblin down to y-level 20, should help i think (edit) i'll make an AFK farm ghast, i'll give some to you after i finish making the farm
oooor, you can just auto-spawn the goblins, till you get one trading the dust, then just exact-copy him That's the way I got my pentacle on DW20 ^_^
They will trade with you if there are Village blocks nearby (wooden doors and a cauldron should be enough) However, sometimes they dont correctly register those, so your best bet is to just make an auto-spawn room in a village or in one of the goblin huts (work as well ^_^) that spawn naturally Just be prepared for a bit of grinding. Also try to get hold of the dust->nugget or nugget->ingot trading goblins when doing this. You will get a lot of bad trading-options with them, which is why I tell you to prepare for grinding them for the one that does sell the dust I think the best trade I got on DW20 was 3 dust for 11 raw steakes or similar. Oh, and the OB trading post /market or whatever it is called might work for these guys as well, so that may be of interest to investigate
I just tested both; I couldn't get the village blocks in a village or outside of a village to work. I believe this mechanic was changed. I did try the trading post from Ex. Util and it worked! So I guess that means I can shut my slave mine down And to confirm ghasts original statement; I've had three hobgoblins with diamond fort III picks mining for over 4 hours now and haven't got any dust [DOUBLEPOST=1426975947,1426972807][/DOUBLEPOST]Update: Trading post only allows you to see the trades of the hobgoblins, you can't actually make the trade with it. So I'm going to try making a village and test that way again.