Thief and Rogue always seemed like too restrictive a term for one of the classes with the broadest possible theme out there. So I think I'll stick with Trickster for now, the same name I use in Olde Skool.
While coming up with the Trickster...Tricks (okay, maybe a different name, we'll see) I was considering how multiclassing might work. Perhaps allowing classes to swap out one of the two "branches" for another classes' (such as the Warrior's Offense/Defense brances for one of the Trickster's). We'll see if anything comes of that idea.
The Trickster's Tricks (*sigh*) will focus, like the Warrior's, on two categories. In this case, Luck (+) and Expertise (-). Both are fairly self explanatory. Luck will be a bit more defensively focused, and Expertise a bit more offense, but both will be fairly broad and meant to be very utility focused. While the Warrior is amazing at combat they need to burn through their cards fairly rapidly in order to pull off their more impressive feats. The Trickster should be more of a long-runner, a lot of their abilities won't require discards or even allow them to use less cards. However, the net results will be less awe-inspiring than the warrior's massive damage capability. While Hearts was the warrior's "secondary" attribute, Diamonds are the Trickster's.
*Takes One To Know One: The Trickster receives a +2 bonus to Card Values to spot deceit or trickery (seeing through a disguise, spotting a sneaking assassin, finding a trap or secret door).
*Exploitative: You receive a +1 bonus to your Card Value when your opponent is making a Difficult roll.
+Dumb Luck: When taking a Difficult action you receive a +1 bonus to the final Card Value for every card you're forced to play.
-Sting Like a Bee: When taking an action against an opponent you can make their resisted action Difficult, but if you succeed you reduce your margin of success by 2 (minimum of 0).
+Deep Pockets: By discarding a Spade you can declare that you have an object on your person. You must have had some means of carrying and concealing the object up until now and it cannot be any larger or more valuable than an ordinary knife or a small book.
-Eyeballing it: By discarding a Diamond you can determine the target number of a Task before you attempt it.
+Bad Aim: In a Struggle, when an opponent fails at an attack against you, you may discard a Spade in order to redirect their attack against another opponent that would be within their range.
-Feint: When you succeed at an attack against an opponent in a Struggle you may choose to inflict no damage and instead get double your Card Value on the next attack you make against them.
+Don't Mind Me: At the start of your turn in a Struggle you can choose to make your action for this round Difficult and in exchange any actions targeting you until the start of your next turn become Difficult as well.
-Never Mind: If you attempt to overcome a Task and fail, you may discard a card to return the card(s) you played to your hand.
+It Wasn't So Bad: After suffering damage you may reduce the damage by half (rounded down), but your next action becomes Difficult.
-Off Balance: When you successfully beat an opponent's action (whether an attack, defense, or otherwise) you can discard a Spade to make their next action Difficult.
+Mulligan!: You may choose to put your hand on the bottom of the deck and draw a new hand of 5 cards.
-Efficiency: When you succeed at a Task, an attack, or a defense then you may choose to swap the card you played with another from your hand so long as the new card would still succeed.
+All In: Discard a Spade at the start of your turn to draw 5 cards. If your hand is above 5 cards at the start of your next turn then discard any extras.
-Wearing Them Down: Every time the Trickster succeeds at an action against another character they receive a +1 bonus to their Card Value for any other actions against them. This bonus increases by +1 for each subsequent successful action. The bonus resets if the trickster fails an action or intentionally takes an action against someone else (so defending against other opponents doesn't count).
+Make It Work: If you fail at a Task or action then you may play a Spade and add it's Card Value to your total Card Value.
-Slow Death: If you succeed at an attack you may discard a Spade in order to inflict the attack's damage again at the start of your next turn. You may discard another spade at that time to continue inflicting damage if you wish.
+Spanner In The Works: At the start of your turn in a Struggle you may discard a Spade to make all opponents action's and reactions Difficult until the start of your next turn.
-Cool-Headed: When you are forced to discard your cards, you may look at the top card of your deck before deciding whether to discard from your hand or your deck.
+Charmed Life: Whenever you succeed at a Task or action, take the bottom card from your discard pile and put it at the bottom of your deck.
Jack of All Trades: When you attempt an action using cards of an inappropriate suite the action is no longer Difficult and just suffers a -1 penalty to the Card Value.