13 I saw coming out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet, three unclean spirits, something like frogs;
three unclean spirits – the kingdom of heaven was cleansed in the fifth bowl of wrath, and the saints were united in the truth. The Prayer of Jesus Christ for the unity of the saints has already been fulfilled. But as we read in Rev 20:7, Satan will be freed and deceive the world one more time, with demons who perform signs.
from the mouth of the dragon…the beast…and the false prophet – this is the deception of Satan described in Rev 9, that comes from the mouth of locusts.