My winning setup was 2 ninjas, 1 cat and 1 knight. The cats help you to chain your special attacks nearly right after when your previous special ends. The knight blocks 75% of the incoming damage. Chain that and you'll get a very effective shield.
Where did the ending go? :( I remember when I first finished the game, there was an ending scene where Ivan, Tevoran and Vadim ended up in jail for mere loitering out of all the crimes they commited.
For whover said there's not enough challenge in this game, try the No_Bazaar_Challenge. Basically you start a new account and never use the bazaar for buying cards, you only use those that you win from the spins. Every day you spin the oracle, you must play 10 games, otherwise you are not allowed to keep the oracle card. The goals are variable, but usually ends at having a no.1 Plat deck with the No_Bazaar account. Here are the details: http://elementscommunity.org/forum/general-discussion/(nearly)-no-bazaar-challenge/