Evade and confidence is pretty much all you'd use it for. Hit evade, spam wither/whirl wind, you're a walking wrecking ball.

You can actually cycle wither and whirlwind, cause more than likely your swing speed is going to be low as hell, so while you wait for yourself to be able to take another swing with the hammer, you can throw in a wither real quick. If you can get your timing down, you'll be crushing spawn and anyone who comes within 3 tiles of you.