In tiebreaker matches and playoff games: the color is chosen by the players themselves, the map template follows the standard scheme, and each player informs the judge about their chosen faction, after which the map is generated. The faction choice for each playoff game does not depend on the number of games played with that faction in previous games. The remaining rules for the playoffs are similar to the rules for the group stage.
With this interpretation, "Mage" can play as Necropolis in all playoff games, and "Might" can play as Stronghold, for example. Is that correct?
This isn't ideal, in my opinion; a 1-1...1-1 scheme is needed, plus (possibly) an exception allowing a previously played faction to be excluded in the next round.
The faction pool should be updated before the final. Something like that...