In Short
Fantasica is all about Events and the Cards. Among Trading Card Games, Fantasica's cards have, by far, the most tangible value.
Game specs
But I'm getting ahead of myself. To begin with, Fantasica itself is a free-to-play game available on both Android and Iphone. It's usually stable, has reasonably fast response time, reasonable update frequency and download times, animated sprites, tactical gameplay, a pleasing soundtrack and for graphics, while the sprites are poor, the artwork on the cards deserve their acclaim.
Gameplay
You can, actually, play without paying anything at all, and given enough hard work, you could do well for yourself. Buying anything is Entirely Optional... but that option becomes at first tempting, then attractive, and then more and more important if you want to compete with other players in Events.
Yes, there's the vanilla (very poor) story line and lots of mass-produced quests for leveling up cards and getting luna (in-game money). Yes, there's even a training route that drains your Training Points which regenerate over time, so yeah, there's milking gameplay too (e.g. you might keep coming back just to use up your regenerated training points). Fantasica's a great TCG. In fact, in terms of core gameplay alone, the Trading aspect of Fantasica far outstrips all other TCGs I've seen on PC or IOS to date, both for its simplicity and its limitations. A great deal of the fun I had in Fantasica was in trading away and trading for cards.
Highlights
Seriously, what earns Fantasica attention and money from players has to be its Events. There are lots of them, sometimes two running at the same time, and more often than not, they're well thought-out, well-programmed and executed. Events offer rewards for various accomplishments (for example, you get a high-class card upon reaching a milestone in score for that event, or a certain number of PVP wins). Generally, these prizes are valuable enough (and tradeable at a price of your asking) to ensure that people find it worthwhile to spend on Event-Specific purchases (special cards with bonuses for that particular event). I honestly believe Fantasica spends more effort designing a single Event than all the main quests and storyline put together.
One of the reasons prizes are so desirable is the trading function. There's tangible value to every card due to the very fact that the prize you win could be either a) built up and used to win more prizes in the future, or b) traded for in-game items that could be traded in turn for other cards that could seriously improve your overall power and thus increase your earning (win more) power more quickly. Though the trading system limits your options to specific in-game items, there's already a balanced economy of cards and in-game potions/elixirs going on.
Downsides
But be warned; competition is steep. Very steep. Don't ever expect to win top prizes in any event short of spending hundreds of USD. Buying the card packs that contain the cards you want would cost real money. Usually, the ones that give the best chances for the best cards would cost between 15-30 USD each. And yes, while you can keep the cards you get and use them again and again in the future, the event bonuses only work for that particular event, which usually ends in a few days.
And yes, people do buy them. A lot of them. It's crazy.
This money-demand is probably its biggest downside. Eventually people smack themselves in the head for wasting too much time and money on Fantasica only to find themselves stressed and struggling to win just that much more to gain that much more, and spend even more to remain competitive. Once Fantasica becomes stressful rather than fun, people have a tendency to quit.
Bottom line
For a hardcore Trading Card Game, Fantasica excels with generally sweet artwork and tangible value in trading cards.But for a free player looking for leisure and fun, it quickly turns into little more than an ad-filled grind.