Ahhh okay! I think I get what you mean. Cthulu-mind-bending-terror? That COULD work, but I'd probably apply that aesthetic to the demons of the Dragon Age world. So bummed they didn't make the Forbidden Ones more unique in their design. Sigh.
I think what terrifies me more are things that are INTELLIGENTLY insane/ psychotic/ sociopathic. It's just that bit human that makes you question yourself, question them and their intention, and their very human unpredictability. They might have pity on you, they might feel an emotion, but it's a fleeting moment. And then the madness kicks in.
While creatures or things in the dark are frightening, I think man's capacity for evil is the most horror inducing thing I can imagine. Definitely get what the stuff from the corner of your eye and the like appeals to you though! Definitely a good source of inspiration.
This.
What is truly terrifying is the prospect of a mortal confronting the Divine and seeing the horror of his own reflection. The elvhen pantheon has the potential to enact such a gaze. That would be a powerful story. The villains would be fully-toothed but understandble--terrifying in their excess but with motivations that are not alien, with desires that are all too familiar,
Moreover, yes the "glitter pantheon" is hyperbolic, but even so, it speaks to a primal sense of power, eros, excess, and tragic decay. There are so many tantalizing pieces of pantheon's story: the relationship between Dirthamen and Falon'Din as something so poetic and deep and tragic and dark. That they are forever interlaced. It's thorny and compelling. Andruil's story. The tale of Ghil'nain's apotheosis, which marries scientific discovery to horror to sublime and sacred knowledge.
The Inquisition, in game, is very concerned with questions of power and how powerful institutions change the arc of history. Cassandra asks if you are doomed to repeat the past. Solas struggles with the proposition that change can actually happen. Can the march of history actually be progressive, or will it just circle back on itself like a snake eating it's own tail?
Making them alien horrors would be so, so disappointing. See also gross, boring robes. DO NOT WANT.
Also, I am on the Falon'Din/Dirthamen/whoever ship and I am not getting off.