Harry gets the chance of his nerd life to go up against every known Sith Lord to exist, one at a time (healed up between each match). He'll get to go up against each version of them too (so movie and EU Vader as an example).
Scenario 1: Current Dresden at his best, no prep.
Scenario 2: Current version, but Dresden is given one day of prep before fighting.
Which can be beat, which does he lose to, and how far can he go? Also, what humorous witicisms can you hear him saying during his bouts?