Well, it depends on how much you want to rely on Master Mirror - if you put most of the amazing golds SK has on your deck, then play MM, you aint getting those and will probably get one that might provide even less value than a 4p bronze.
i did check all factions legendaries cardpool individually, solely for this card, and i did use a SK MM deck, but that is just because its my favourite faction.
The best factions for it are probably NR or MO, where you will get great value almost guaranteed, without requiring synergy from your deck.