Seal cards

Is there anyway to get seal cards without paying real money that seems really stupid you can't get common Seal cards without money how would you ever be able to get monsters

once you get to floor 3 you can fight bosses and collect boss essence. It costs 25 boss essence for 20 seal cards.

Thanks nice I'm on floor 2 right now but so far there hasn't been any monsters for capture

You can only capture monsters on the first floor