To everyone, to get the husk of the pit (first form of the necrochasm) do the mission "Fist of crota" on the earth. Next, right as the mission starts skip to the blade of crota. Kill the knight and you will have a chance for the husk of the pit to drop. It does not matter what level the mission is set to, however you may have to try a couple of times before the gun drops. Your welcome. :)