Revelation 20:10, 14

And the devil who had deceived them was hurled into the lake of fire and burning brimstone (sulfur), where the beast (Antichrist) and false prophet are also; and they will be tormented day and night, forever and ever.

Then death and Hades [the realm of the dead] were thrown into the lake of fire. This is the second death, the lake of fire [the eternal separation from God]. [Matt 25:41; 1 Cor 15:26]