You have him slowly build his advantages in the background, interspersed with a few key meetings with the hero that are inconclusive and tantalizing. Then, in the latter portion of your story, you have him unleash his full, awful might, rolling over all the established story and setting and characters that the audience has grown to love, ruining them and bringing them low. You have him win, and keep winning, over and over again, until at last there seems to be no hope at all. But the hero maintains hope against all odds, believing even when belief seems foolish. Then a secret is revealed, a truth is uncovered, something previously unknown is made known, and a chance appears. The hero takes that chance, stands before the villain. The villain still seems mighty, but now unsure. He unleashes his full might upon the hero, but now the hero takes the chance, does the impossible, and just when the villain seems at his mightiest, the hero turns the tables, and snatches victory from the jaws of defeat. The villain is defeated utterly, reduced to smoke and fog, and banished from the world forever, never to return.
At least, that's how I think you should do a villain of the Lich's caliber.