When the 1,000 years are over, Satan will be set free from his prison.
References for Revelation 20:7
He will go out to fool the nations. He will gather them from the four corners of the earth. He will bring Gog and Magog together for battle. Their troops are as many as the grains of sand on the seashore.
They marched across the whole earth. They surrounded the place where God's people were camped. It was the city he loves. But fire came down from heaven and burned them up.
The devil, who fooled them, was thrown into the lake of burning sulfur. That is where the beast and the false prophet had been thrown. They will all suffer day and night for ever and ever.