This is the return of Christ (hinted in verse 15), and the final great battle that ends man’s existence.
Rev 16:12 (Sixth Bowl)
the water was dried up – there are many who say the water of the Euphrates is already drying up in preparation for the Kings from the East to cross. See also Rev 9:14.
three unclean spirits – the kingdom of heaven was cleansed in the fifth bowl of wrath, and the saints were united in the truth. The Prayer of Jesus Christ for the unity of the saints has already been fulfilled. But as we read in Rev 20:7, Satan will be freed and deceive the world one more time, with demons who perform signs.
from the mouth of the dragon…the beast…and the false prophet – some kind of deception of Satan, through the speaking of “the mouth.” God has carefully protected His mystery in the Book of Revelation for all to see in the end times. But Satan, who is the father of lies, will twist the truth, in the last days.
gather them together for the great day of God, the Almighty – this is the great day of His wrath, mentioned in Rev 6:17, 9:15.
Behold, I am coming like a thief – at any moment now Christ will return to take His chosen ones home. His chosen ones remain until this final deception. The great day is a battle against Israel, which will be completely saved, as we studied in Rev 7. The King of the North, Gog, will come against Israel. We are just waiting for Christ to take His chosen ones out, as it were, passing through the Red Sea. And “all the nations will weep and mourn” (Rev 1:7).
Blessed is the one who stays awake – the final encouragement of Christ is to keep oneself ready for this moment. Do not be deceived, along with the world, by the final lying signs and wonders.
Har-Magedon – Armageddon is the Greek form of Megiddo. This is the Megiddo, mentioned in Zechariah 12:11, “in that Day (the Day of the LORD), there shall be a great mourning in Jerusalem, like the mourning at Hadad Rimmon in the plain of Megiddo.” The repentance of “the inhabitants of Jerusalem” is the last event that precedes the return of Christ. The meaning of “and they shall be together to the place called in Hebrew “Armageddon,” could refer to the place that the nations gather. But the more likely meaning is that the nations gather together, when the “inhabitants of Jerusalem” repent.
upon the air – the speech is “upon the air.”
a loud voice saying “it is done” – the voice of the Spirit of Christ, likely speaking for the invisible God, see Rev 21:6, “It is done.”
peals of thunder – in Rev 19:6, the peals of thunder say “Hallelujah! For the Lord God Almighty reigns!”
a great earthquake – a great war, see also Rev 11:13 which described the war that killed “a tenth of the City” who died in the Reformation and ongoing religious wars. This “great earthquake” destroys a third of mankind as mentioned in Rev 9:15.
the great City was split into three parts – Mystery Babylon is compared to the idolatrous Israel, who God judged in Ezekiel 5:2: “you shall burn with fire 1/3 in the midst of the city, when the days of seige are finished; then you shall take 1/3 and strike it around with the sword, and 1/3 you shall scatter to the wind…”
every island fled way… – possibly the effects of Nuclear blasts.
hailstones, about one hundred pounds each – the hailstones of Rev 8:7 were metaphorical of “sores” on those who worshiped the image of the beast and received his mark. These great hailstones are metaphorical of the absolute destruction of Babylon. The great earthquake and hailstones are also described in Ezekiel 38:18-23. God used large hailstones to destroy Israel’s enemies in Joshua 10:11.