Henchmen are hired Wizards that help you in a duel and they can only be purchased while you are in combat. They will come to your aid and behave similar to your Minion, only stronger and smarter. They will act in the same round that they are summoned by the player, and will disappear once the duel has ended.
If you want the prize, you have to build the ladder rung by rung. There are no shortcuts.