King James Version
And his power shall be mighty, but not by his own power: and he shall destroy wonderfully, and shall prosper, and practise, and shall destroy the mighty and the holy people.English Standard Version
His power shall be great--but not by his own power; and he shall cause fearful destruction and shall succeed in what he does, and destroy mighty men and the people who are the saints.New International Version
He will become very strong, but not by his own power. He will cause astounding devastation and will succeed in whatever he does. He will destroy the mighty men and the holy people.