17:13"These have one purpose and they give their power and authority to the beast.

The description of the ten horns (KINGS) continues from the previous verse .

"These have one purpose

Usually political kingdoms can't agree. Consider how many countries have been formed due to ethnic differences alone. Even in the Mideast where one would hope to find unity among ethnic lines, we find many splinter (often violent) organizations. So something unusual has taken place to cause this oneness of purpose.

and they give their POWER and AUTHORITY to the BEAST.

Strange way to put this since the BEAST is a "puppet" regime too (Revelation 13:2). Or another view, the devil uses these 10 short-term rulers, powers, and world forces of this darkness (Ephesians 6:10-20) to fulfill Revelation 13:2.