A.T. Robertson Commentary Revelation 20:14

"And death and Hades were cast into the lake of fire. This is the second death, [even] the lake of fire." — Revelation 20:14 (ASV)

Were cast (εβληθησαν). As the devil (20:10) followed the two beasts (19:20) into the same dread lake of fire. Death is personified and is disposed of, "the last enemy" (1 Corinthians 15:26) and Paul sings the paean of victory over death (1 Corinthians 15:54f. , from Ho 13:14). Hades has no more terrors, for the saints are in heaven. There is no more fear of death (Hebrews 2:15), for death is no more (Revelation 21:4). The second death (2:11; 20:6; 21:8) is here identified as in 21:8 with the lake of fire.