for me... I'd think for Doomed Ones, I would probably pick "the right wrong" from the Deer hunter
that would be its opening!
using the power of theatre of the mind, imagine visuals that play around being turned upside down or having the clip reversed to change the context of the scene (a character that appears to be falling, or being pulled down, but in reality, they are being pulled up, ascending). or a scene with elder monsters disintegrating a world, when in reverse, they are making one (ties into the time travel aspect of DO, and perspective)
also right wrong is just an amazing song :u
an ED would be something like.... which sounds like a generic choice
Goodbye to a world, by Porter Robinson
how this would look, for the ED is an alternative world (or foreshadowing) where the primordials (ultimate "big bads" of the comic) successfully overthrow the gods and destroy literally the entire world, before looking to the dark one, eldritch horrors looking into her soul, the soul of the person who had freed them and saying.
_"thank you,
I'll say goodbye soon,
though its the end of the world,
don't blame yourself"_
something like that.
what would yours be?
(edit: also, you should link your comic so I can get some semblance on your reasoning)