black formal mermaid dress Satin Off the Shoulder Long with Slit the gown is of professional quality weight Strapless Beaded Bodice Mermaid Gown

Both are great here

The black robe with red details symbolised the unity between heaven and earth, according to Siumerghe

Make it a full spread

But maybe

How do I keep a summer wedding guest dress formal without feeling overheated

A velvet formal dress in burgundy or deep emerald for an October event is doing multiple things simultaneously: it keeps you warmer than satin would, it photographs richly under falls warm light, and it looks intentional rather than just I wore a formal dress to fall. The nap direction thing: velvet looks different depending on which way you run your hand across it, and quality velvet accounts for this in the cutting process