Annihilationism seems like a swift and merciful fate in contrast to the following.
Revelation 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.
in Rev 20:10 it is the devil (Satan, the devil in Rev 12) and the false prophet (which is a symbol for something in the book of Revelation) that do the suffering "day and night forever and ever". If we limit the discussion to just humans - then we have to go to the 3 angel's messages in Rev 14 - where we find this in the third angel's message.
Rev 14
9 Then another angel, a third one, followed them, saying with a loud voice, “If anyone
worships the beast and his image, and receives a mark on his forehead or on his hand, 10 he also will
drink of the wine of the wrath of God, which is mixed in full strength in the cup of His anger; and he will be
tormented with fire and brimstone in the presence of the holy angels and in the
presence of the Lamb. 11 And
the smoke of their torment
ascends forever and ever; they have no rest day and night, those who worship the beast and his image, and whoever receives the mark of his name.” 12 Here is the perseverance of the saints who keep the commandments of God and their faith in Jesus.
So the "only place" where this phrase about "torment..forever" is specifically applied to humans is in Rev 14 and there it is the "smoke ascending up" forever. What is more the entire process of that smoke ascending up forever happens "IN the presence" of the Lamb and not only that - but also "in the presence" of the Angels. They are all stuck there at the brink of hell for as long as one might suppose this to last. With the wicked torment ascending up "in their presence".
What is more - Rev 14 starts off with a description of the 144,000 who are also with the Lamb at that time.
Rev 14
Then I looked, and behold, the Lamb
was standing on Mount Zion, and
with Him 144,000 who had His name and the name of His Father written on their foreheads. 2 And I heard a voice from heaven, like the sound of many waters and like the sound of loud thunder, and the voice which I heard
was like
the sound of harpists playing on their harps. 3 And they *sang a new song before the throne and before the four living creatures and the elders; and no one was able to learn the song except
the 144,000 who had been purchased from the earth. 4 These are the ones who have not defiled themselves with women, for they are celibate.
These are the ones who follow the Lamb wherever He goes. These have been purchased from mankind as first fruits to God and to the Lamb.
So then they two are stuck at the brink of hell for the entire duration of it.
As for Rev 14 "
smoke ascending up forever" -- John is borrowing an
OT term for a finite event already known to his reader.
Is 34:
8 For the Lord has a day of vengeance,
A year of retribution for the cause of Zion.
9 Its streams will be turned into pitch,
And its loose earth into brimstone,
And its land will become burning pitch.
10 It will not be extinguished night or day;
Its smoke will go up forever.
From generation to generation it will be desolate;
None will pass through it forever and ever.
11 But pelican and hedgehog will possess it,
And owl and raven will dwell in it;
...
13 Thorns will come up in its fortified towers,
Weeds and thistles in its fortified cities;
It will also be a haunt of jackals
And a habitat of ostriches.
14 The desert creatures will meet with the wolves,
The goat also will cry to its kind.
Yes, the night-bird will settle there
And will find herself a resting place.
15 The tree snake will make its nest and lay eggs there,
And it will hatch and gather them under its protection.
Yes, the hawks will be gathered there,
Every one with its kind.
John is using the same "Smoke goes up forever and ever" term in Rev 14 as his readers already knew about in Is 34 - describing a finite event where animals then later come to find a dwelling place in the very area said to have smoke going up forever and ever.