Board Thread:Question and Answer/@comment-76.69.226.145-20160430175705/@comment-26494010-20160430185603

If you clear the Celestial Realm 10-6, you can increase your card limit by 15. That is the ONLY way and this happens once. After that, you must use jewels for more card space.

As for your N cards, you can really toss all of them if you can fill your teams with all R cards and up.