John's account of the origin of the invaders is followed by a vivid description of them (just as for the locusts). The description only heightens our sense of terror as we move from the fifth trumpet to the sixth. The horses John sees are not simply a means of transportation for human soldiers. Horses and riders are described together as one complex and terrible creature, like the centaur of Greek mythology. They are not human but demonic, and their job is to carry out the commission of the four angels from the Euphrates to kill a third of mankind (v. 15; compare v. 18).

While the locusts in the preceding vision had "tails and stings like scorpions" (v. 10), these horses had tails like snakes (v. 19) with similar power to injure (again, see Jesus' promise of authority over both "snakes and scorpions" in Lk 10:19). Even worse, out of their moutes came fire, smoke and sulfur, viewed as three distinct plagues bringing death to one-third of the human race (vv. 17-18). If the first four trumpets brought "fire" on the earth (8:7, 8, 10), and the fifth, "smoke from the Abyss" (9:2), the sixth adds sulfur to the conflagration. These three plagues of fire, smoke and sulfur (v. 18) will become basic elements in John's subsequent visions of eternal punishment (compare 14:10-11; 18:9, 18; 19:3, 20; 20:10; 21:8). "Sulfur" in the King James Version becomes "brimstone," creating the expression "fire and brimstone" for preaching based on the fear of hell.