A video look at this coming month's White Dwarf gives us a look beyond the Tau and Necromunda.
Looking past march... Ancient Evils........ Sounds like Necrons to me, but possibly both Necrons and Dark Eldar?
Video via The Dark Artisan - you can check out his Youtube page and additional videos here
https://www.youtube.com/channel/UClbmK5kNUd2-bzH9fjlFgpA