The import of this verse should be clearly grasped if Revelation is to be understood. It rapidly surveys the wind-up of all things. Seeing that this is the great judgment book, the winding-up of judgment comes first in the verse.
The reward of His servants the prophets, the saints, and them that fear His name, small and great, comes next, not in order of time, but in moral order. The destroying of them which destroy the earth is the clearing of the earth of evil, so that those who are to be rewarded may have their place in the coming kingdom, just as the flood destroyed those who destroyed the earth, and thus prepared the way for Noah's place in the new earth of that day.
To make it clear, the first half of the verse carries us on to the great white throne, which is the final act of judgment, and takes place on the threshold of the eternal state, whilst the second half is chronologically earlier, and leads up to the battle of Armageddon (Rev. 19), the siege of Jerusalem (Zech. 14), the sessional judgment of the sheep and the goats (Math 25), and the setting up of the millennial reign of Christ (Rev. 20:44And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years. (Revelation 20:4)).
The clear grasping of the meaning and place of this verse is a great help.