As you may know, in the dark below you can evolve weapons to make them better. One example of this is the necrochasm. When you recieve the common version of necrochasm, it may seem useless. That is still not a weapon to discard. Once you reach the required eris rank, you can purchase an item for ten black wax idols to upgrade it to a legendary. Cool! But i want my exotic! To upgrade to the necroshasm, you will need a crux of crota. Eris does not sell this matierial. It is likely that you will. Need to complete the hard raid to obtain this. That would make it similar to the mythoclast, but with a few more steps. But wait a second! Why would bungie exclude the most sought out gun in the expansion for a whole month? That just doesn't make any sense. My theory is that the crux of crota can be obtained in the normal raid, making it much easier to get. This is just me thinking logic, comment your opinion on the topic.