Talk:Transcendent Science/@comment-24053170-20160912201922/@comment-24053170-20160913020525

Technically speaking they created the metal (Necrodermis) after studying the C'tan. Also necrodermis is not truly invincible as it cannot survive the touch of the warp, and Ciaphas Cain managed to permanently destroy a fleet of Necrons despite the necrodermis by blowing up a promethium refinery.