Add checkboxes with mods when playing with friends.
I few option:
*Hand Showwed
*10 Cards on hand no deck
*No timer
*Custom Deck for both players (to hand picking the cards in the deck instead of choosing a set)
*Personal Decklist (like in a deckbuillding game)
The idea is have a lot of variants for playing with friends. If the mode is popular it could be made Competitive.