JRR Tolkein uses borrows the motif of eucatastrophe from Scripture. It’s a providential reversal of fortunes for God’s people and against God’s enemies. One of the most obvious is the story of Mordecai and Haman in the book of Esther. The ultimate eucatastrophe is described in 2 Thess 2:1-12, Rev 16:13-16, Rev 17:11 , and 20:7-10 where the Man of Sin (and embodied image of the False Prophet) comes to lead government-sponsored persecution of the worldwide church. He and his followers (all unbelievers) will be consumed by Christ’s second coming. A picture of this is given to us in the Old Testament when Pharoah’s army is consumed by flood in pursuit of the Hebrews. This time, however, the destruction will come by fire.
 Har Magedon is translated as “Mountain of the Assembly” ie the church by Meredith Kline