My thought process was that a single high level blackbelt can take out any single powerful enemy in the game, especially if Hasted. The three black mages can take out any group of enemies with high level multi target spells like nuke. I figured this team would be the fastest to take care of any single battle it could face. No boss could handle a level 50 master with Haste. No pack of enemies can handle three successive nukes. Four Black Belts wouldn't have quite the same capabilities.
