Some idea
Maybe a character with more card to choose from
Card with effect one more than one turn, like a card that steal 8% of the enemy size at the end of 3 turns, or maybe card that do nothing but when you get three of them, it do something powerful, long casting cards to, or maybe card that add trash card to your opponent, maybe you can try to find inspiration from game like frien vs friend, where your hand of card can be affected by th opponent or slice and dice, with card with keyword effect
Maybe a passive ability where he character use the unused card of the opponent