Yo! I'm actually the player in question, and I appreciate the feedback! I admit that I'm not particularly familiar (read: at all familiar) with the Dresden Files system, unfortunately, though I hope to be rectifying that shortly.

The idea for the deck was that, as Pole had already said, the character would feel a compulsion to draw a card at a regular interval, with the card drawn affecting the character in a given way until the next card was drawn. One of the things that I'd considered is having the effect of the cards not necessarily be immediately obvious; for example, to everyone (including the person drawing the card) it would look like a normal playing card, and it would be left to experience to figure out what benefit (or malediction) the character gets. So the character may draw a card and say, "Well, nothing seems different." until he realizes that gouts of flame are spitting from his mouth. In addition to this, the entire deck appears blank until it's time to draw another card (so no stacking the deck!)

Some ideas that I had were to have the suits and colors of the deck be attuned to respective "families", or things they represent, insomuch that red suits and black suits would internally have similar affects to each other, but distinctly different ones from the other color. Same for suits. It would give a form of structure to the deck, rather than "I pull this ability out of nowhere when I draw a card". We'd discussed the possibility of using fudge dice to determine whether the affect on the character was positive, negative, or miscellaneous.

An example might be that Red cards affect the character's body, and the suit of Hearts affect it in a "natural" way, so a red hearts card might affect the character's toughness, stamina, strength, speed, etc. So if they got a card that affected their toughness, they might get supernaturally tough, or they might get a temporary case of hemophilia. Or they might be able to drink a bunch of booze without becoming wasted (Neutral).