Urban Rivals has a deck of only 8 cards, which in each match both players draw 4 and use only those 4 cards for the rest of the game. It works well, though. In fact, Urban Rivals is one of the biggest CCG online which has a lot of fanbase. What it differs from your idea in the first post, though, is that there is no reusable card in Urban Rivals in a match. Each rounds, a player choose 1 of their own cards againts to fight against each other (all cards are Characters, by the way). The used cards can't be used in the remaining rounds. So, each match consists only 4 rounds unless a player has run out of LP before the 4th round occurs.