I think that is why they came out as repulsive flesh mountains. Beings of the Void manifesting in a physical state just isn't right. Its not gonna be pretty. Kind of like how the monster from Steven King's IT manifests as a giant spider. Its the closest thing to its true form the human mind understand. Old Gods formed in the Void don't translate well to physical reality, and come out as shapeless blobs of flesh, eyes, mouths, and tentacles.
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Idk about extinguishing suns. A planet sized titan would be smaller to a sun than we are to them.