"And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him. And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of His Christ: for the accuser of our brethren is cast down, which accused them before our God day and night." Rev 12:9-10

Dragon - Beware of his cruelty
Serpent - Beware of his craftiness
Devil - Beware of his corruption
Satan - Beware of his contention
Deceiver (RV) - Beware of his cunning
Accuser - Beware of his complaint