It’s clear that Satan, the antichrist and the false prophet are all thrown into the “lake of fire” and tortured forever, and those whose names are not found in the book of life are thrown into the same place after the Great White Throne judgment.
You’re correct that it might be some sort of unknown torture, but the “rich man” in Luke 16 was wanting Lazarus to bring a drop of water to cool his tongue from the “phlox” (flame) he was experiencing. So it felt like torturous flames to him.
Also, the dead “stand before,” “histemi enopion,” God.
Rev 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
Rev 20:11 And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
Rev 20:12 And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.
Rev 20:13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
Rev 20:14 And death and hell were cast into the lake of fire. This is the second death.
Rev 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.
And again I think these references to lakes of fire can be explained as metaphorical imagery that the people of the time could understand, the torture of being burned. It is not a randomly occurring singular metaphor either.
“Rev 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.”
Now, I sincerely doubt such a place as hell would have a sun that it orbits around to create what we know as ‘day and night’. There would be little purpose for God to create such celestial objects in this realm, less need for anyone in hell to need a day or a night. This is poetic license.
Or the book of life. Humans read books for reference and instruction. Would God need to have books be opened to have people’s works listed? He is omniscient. This is not a literal opening of books that God will have done at the time of Judgement, but a metaphor for people’s works being of focus at that time.
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