So here's a thought:
Each player has two decks, a Hero Deck of Heroes, Classes, and Equipment and a Challenges Deck made of Monsters and Traps. At the start of play, each player randomly selects ten cards from their Hero Deck, this becomes their Treasure Horde. Each player draws X cards for their starting hand and places the top card of their Challenges Deck up. The Challenge Cards have an obstacle to be overcome with a list of requirements the Hero must meet to overcome it. A Trap Card might read: Disable Device 5 OR Magic 10 OR Strength 18 AND Health 50. meaning a weak thief hero might bypass it easily, a Wizard or Cleric might need to be of moderate power, and a Fighter would have to be fairly burly. If a hero can't bypass a challenge, they can be permanently buffed by playing a Class Card (Class Cards would be something like, Rogue +2 Sneak, +2 Disable Device, +4 HP) or temporarily buffed for the challenge by playing an Equipment Card (10ft Pole +2 Disable Devices, Flaming Sword +2 Strength, Wand of Armor +2 AC +2 Magic). Equipment Cards are discarded after solving a challenge. Once a player defeats a challenge they draw one of their treasure cards, discard any equipment cards on their hero, and their opponent plays another Challenge Card from the top of their Challenges Deck.
Cards:
Heroes:
Heroes are used to acquire Treasure by solving Challenges.
A hero's stats are determined by their race, class, and other sundry bits.
Classes
Classes are played on heroes to upgrade their abilities. Once a Hero meets the requirements he's eligible for a Prestige Class card, like Elf, Arcane Spellcaster, Martial Class, you can play Arcane Archer on them.
Equipment
Equipment is expended when solving a challenge but allows anyone to solve any challenge if you're willing to spend the cards to do it.
Traps and Monsters:
Traps and Monsters provide the challenge for the other player to overcome.
I haven't come up with an elegant way of removing heroes from play yet. Maybe each way of bypassing a trap or monster has a HP Cost that is deducted from the hero's total. You can play, like, Potion of Cure Light Wounds to pay the cost for you but it isn't avoidable otherwise.