Bro. I think with 'Packs', any cards be picked (even not unlocked girls. With Mythic/legendary Pack (World Bosses) - i have definitely have picked new girl in event (Court Ladies) without having unlocked rooms in girl event.
With colosseum, i don't think this fact is changed BUT they have double yield than normal base numbers i.e. Common 1750, Rare 1400, Epic 1050, Legendary 700, Mythic 350; with chance to get higher number of cards (Maximum roll that i have found is 4 times than base yield)
