Jokers can be added and removed by following the instructions above to show the popup, then clicking the + and - buttons next to the joker cards. By default, cards are available for red and black jokers but with 0 cards added.
To create a "mega-deck" with multiple decks combined, follow the instructions above to show the popup, then simply add multiple copies of every card. Use the "All +1" button to quickly add an additional copy of every available card.
If you'd like multiple separate card decks, click a deck in the bottom popup to add an additional deck token. Read more about custom card decks
Cards can be removed from the deck to create a stripped deck. Cards can be added and removed by following the instructions above to show the popup, then clicking the + and - buttons next to each card.