I have played various card games since I was small: War, solitaire, go fish, Uno, then later rummy, gin, hearts, poker, blackjack, and canasta. Along the way, I discovered Tarot cards; better decks have a wonderfully mysterious ambiance that makes you want to believe they have power. Years later, trading card games were introduced, and again I was enthralled, combining the fantasy of the mystical with gaming and chance. Short, simple game play and lack of depth or elegance eventually dulled the charm of even those, though.
Since that early exposure, a variety of anime and children's shows themed around trading card game experiences have emerged. Most are mediocre, but they do present some interesting concepts. The thin exposure I have had to those shows, and the slightly deeper exposure I have had to actual trading card games and tarot have all been left to percolate and now things are bubbling!
The Cards:
The pigments and surface treatments of the cards are compounded from various materials ranging from minerals, plant extracts, lard, blood, bile, ichor, etc. The potency of such compounds are usually related to the nature of their source, the synergy they create with other ingredients and the card stock itself.
In general order of potency, not withstanding the natural properties of the source :
- Thick paper
- Woven fiber
- Leather
- Wood (solid or plied)
- Metals (enameled, etched, engraved, and/or stamped)
- Scale, Horn, or Bone (solid or plied)

More sophisticated cards, made of lacquered cloth, leather, or wood, usually have greater capacity for energy transfer, so the extent to the effects are far greater. The imagery is usually more refined, with moderate glyph-work. Some of these cards are simply improved versions of the simpler paper cards, but the greater energy potential allows effects such as curing or inducing paralysis, pain, or unconsciousness; electrical shocks; etc. Cards with this level of workmanship are rarely intended to be consumed when used.
Metal cards can be relatively simple, but are usually inscribed, etched and/or enameled with ornate illustrations and complex glyph-work. The durability of metal cards makes them ideal for fiery uses, and their natural conductivity allows them to produce large effects. The simplest metal cards are often used like modern lighters or flashlights, with more sophisticated cards being used for small pyrotechnics. The most elaborate metallic cards can produce large destructive effects. Generally speaking, because of the attributes of metallic cards, they are not used medicinally.
Scale, bone, and horn cards tend to be particularly potent if the sources are creatures with natural energies. These cards are usually the most ornate, with intricate illustrations and glyph-work, usually rendered in pigments made of the various fluids from the same creature that was used to make the card-stock. This class of card is often used to summon creatures or manipulate whatever natural energies the donor creature had.
Card Casting:

Card-casting is done by holding a card appropriately (don't point that fire-jet card at your head!), and either invoking aloud or focusing inwardly on the card's glyphs to push energy into and through the card.
The Craftsmen:

Students also make stacks of disposable igniter, glow, and charm cards, as well as various other cardsets to be sold off or traded for other goods and services, offsetting the cost of apprenticeship.
Application:
I envision card-casting soldiers with small decks of cards crippling, burning, and electrocuting in combat, or using cards to tend the wounded; master craftsman card-casters using cards to precisely shape stone and assemble buildings; town doctors using cards to tend to the ills of the community; and so on.The images in this post have been culled from the internet over the years. If you own the images or know who does, please let me know and I will properly attribute or remove them.