(as) black as a raven's wing simile
A raven is one of several larger-bodied species of the genus Corvus. They consist of multiple species within the genus.
The term "raven" is distinguished from "crow" merely by the ravens' larger size; the two share the same genus.
If something "is as black as a raven's wing", it is intensely black or completely dark, entirely devoid of color or light.
When the movie was over, the theatre became as black as a raven's wing.
Those dangerous criminals will be sent to a prison which is as black as a raven's wing, spending the rest of their lives on repenting of their sins.
If something of a person becomes/turns "as black as a raven's wing", he/she/it displays a propensity to be mean, selfish, malicious, petty, or wicked.
I can figure out the malicious look in his eyes. They suddenly turn as black as a raven's wing.
She came up with an idea that I couldn't accept because it was as black as a raven's wing.
The inexplicable or concealed place or state indicates the afterlife.
I'm very sorry for your dad. He's beyond the veil.