A.T. Robertson Commentary Revelation 18:8

"Therefore in one day shall her plagues come, death, and mourning, and famine; and she shall be utterly burned with fire; for strong is the Lord God who judged her." — Revelation 18:8 (ASV)

Therefore (δια τουτο). Because of her presumption added to her crimes.

In one day (εν μια ημερα). Symbolical term for suddenness like μια ωρα, in one hour (18:10,16,19). John has in mind still Isa 47:7-9.

Shall come (ηξουσιν). Future active of ηκω. Her plagues are named (death, mourning, famine).

She shall be utterly burned (κατακαυθησετα). Future passive of κατακαιω (perfective use of κατα).

With fire (εν πυρ). "In fire," as in 17:16.

Which judged her (ο κρινας αυτην). Articular first aorist active participle of κρινω referring to κυριος ο θεος (the Lord God). The doom of Babylon is certain because of the power of God.