In the midst of the living creatures was the appearance of glowing coals of fire, or of torches. Fire moved back and forth between the living creatures; it was bright, and lightning flashed out of it.

2 Thessalonians 1:7
and to grant relief to you who are oppressed and to us as well. This will take place when the Lord Jesus is revealed from heaven with His mighty angels

Revelation 4:5
From the throne came flashes of lightning, and rumblings, and peals of thunder. Before the throne burned seven torches of fire. These are the seven Spirits of God.

Psalm 104:4
He makes the winds His messengers, flames of fire His servants.

Ezekiel 10:2
And the LORD said to the man clothed in linen, "Go inside the wheelwork beneath the cherubim. Fill your hands with burning coals from among the cherubim and scatter them over the city." And as I watched, he went in.

Daniel 7:9
As I continued to watch, thrones were set in place, and the Ancient of Days took His seat. His clothing was white as snow, and the hair of His head was like pure wool. His throne was flaming with fire, and its wheels were all ablaze.

As for the likeness of the living creatures, their appearance was like burning coals of fire, and like the appearance of lamps: it went up and down among the living creatures; and the fire was bright, and out of the fire went forth lightning.