The Lord has not revealed what these signs are. We also have no reason to think that the devil would limit has repertoire of signs to a couple of selections. As he does his deception over the centuries of the new dispensation, in changing times and varying cultures, it is to be expected that the devil would charge his demons to keep changing things up. Whatever the signs are, they are sufficient to convince gullible people that what comes from the “mouths” of the dragon and the beast and the false prophet is reliable (Revelation 16:13).
14 For they are demonic spirits, performing signs, who go abroad to the kings of the whole world, to assemble them for battle on the great day of God the Almighty.