In Revelation 20:10, where was the devil who deceived the nations finally thrown?

Answer: The lake of fire and sulfur

The devil who had deceived the nations was thrown into the lake of fire and sulfur (KJV: brimstone), to be tormented forever.

“And the devil who had deceived them was thrown into the lake of fire and sulfur, into which the beast and the false prophet had already been thrown. There they will be tormented day and night forever and ever.”— Revelation 20:10 (BSB)