Nekros was temporarily called necros during development. The name Nekros was revealed with Update 10.0.
Nekros' concept art originally showed tendrils hanging from his head and shoulders. When Update 10 was released the tendrils were removed, but made optional as a Nekros-only Syandana named the "Mortos Syandana". However in Update 16.5, the Mortos Syandana received its own auxiliary cosmetic slot and was renamed the "Mortos Binds".
Forma is highly advised to use on Nekros' Aura polarity to gain more mod capacity that he otherwise wouldn't have.