Too much info for card?

With the previous tip, you might be able to fit all information on the card, but whether you use icons or not, there's probably a very steep learning curve to this game. I personally don't enjoy games that require you to keep track of so many rules and stats.

Is there any way you can bring down the amount of data you include on the card without compromising your game?

I haven't seen the art or the complexity of the rules, so I can't be sure. But a reference sheet that includes both the symbols and a very brief summary would definitely improve the chance of me giving such a game a go.

That is a substantial improvement, though still a lot of information to fit onto a standard playing card. I made a game a while ago which has about half of the info you're trying to fit on, and even that was pushing it for how small I could make the text and symbols to still be readable. For info, I used just over half of the area for artwork.

Is it possible to split the info for the two game states (enemy, allied) onto the front and back of the card? So when it becomes Allied you flip the card over and keep it. This would greatly reduce the amount of info, and more importantly it would present only the relevant info to the players. Presenting irrelevant info (i.e. the Allied info when it is an enemy, or the enemy info when it is Allied) not only takes up space but is also informational clutter that may detract from ease of play.
I know the OP said that these cards are drawn from a deck, so it might not be possible for your game. Just a thought.

Regards,
kos

Moonstruck Trapper – (NEU) (^)
(+) RNG:2, ATK:2, DEF:2, SPD:2, DMG:2, HP:2, XP:1
-Alliance: Defeat.
-Allied: Beast Tamer. (%) Enemy.
Special Attack: Net Drop
Target: untrapped opponents.
(+) RNG: 2, +3 ATK, DMG:0
Success: Trapped
“You’ll fetch a fine price at market!”

I made some assumptions, which I hope I can explain well enough here,

I've replaced a few phrases with simplified keywords. This is an example of a way you can simplify and unify all of your cards to a common template.
In this case Alliance is "conditions required for an alliance"
I condensed the "(%) cannot ally" to a part of the "Allied" keyword, my assumption here is that the effect occurs once the trapper is an ally, so you save a line and the flow of context is maintained.
I changed "hit" under special attack to "success". Again, I assume that special attacks might not always be attacks (healing, removal, etc). Success is a nice broad container for these.
I swapped "NPC Use" to "target". In my mind, a special attack would be targeting something, again, just trying to simplify the text.

you could go a step further and create a keyword to replace "Special Attack". something genre appropriate or even specifically related to the game, or even just "Power". these changes don't require a rule book to flip through mid game and help tidy up the cards too.

It looks like others have said what I was mainly thinking, but I'll just add this.

This is really two problems compounding each other.
It is both a game mechanics problem and a graphic design problem. I'd guess that what tends to make this a real challenge is that most people tend to be good at one or the other, but not both.

I find these problems particularly rewarding to work. For what it's worth, if I find myself truly stuck in this kind of problem, it tends to indicate there is an underlying complexity issue with the basic nature of the game.
Also, this forces you to come up with innovative solutions that ultimately make the game better.

Ask yourself:
Are certain stats redundant? Why aren't they? How would you compensate if you had to get rid of X?
Can I replace a common attribute or phrase with an icon? Set of icons?
What info is the first thing a player will look at? What will be referenced often? -These items should be most prominent from a graphic design perspective.

I have a fantasy game in the works, and one of the challenges was to come up with a system that, even though has a lot of nuances that RPGs are known for, could be described quickly and clearly, and fit on very small cards.

One such lesson in consolidation:
I had a bunch of nifty symbols, but I was still having trouble getting them displayed in a clear, consistent, and space efficient manner.
So I figured out what information had the highest priority. What does a player need to know first when even considering what ability to use? One they decide to use an ability, then what information is most immediate?
Is some info rarely used? Then consider making it able to be inferred without needing a separate icon.

For my game, it turned out players looked at range and damage when deciding what ability to use. Things like damage type, while sometimes important, could get in the way visually when not really needed.
Once they decide to use that ability, the next most important bit of info is what die they need to roll. (Physical and magical attacks used separate dice.)

This led me to design a "targeting bracket" icon that preceded every ability and contained the most relevant info. It turned out I could completely scrap separate icons denoting melee/ranged/cast concepts.
Instead, a single number was displayed on this icon to denote range. It's shape noted whether the attack was a single target or an area effect. And the color indicated what die to roll.
Following the bracket was the ability effect, such as damage. These icons had a shape/color/symbol hierarchy of their own.

So the most important elements are immediately apparent, where something like whether the attack is a spell cast or a melee attack could be inferred when needed for some reason.
An attack that had a range of "touch" that used the yellow physical die could be inferred to be melee. Whereas an attack that has a range of 2 using the magic die could be inferred to be a spell cast.

Similarly, when determining damage, the most important consideration was whether the damage was immediate or an over-time effect. So, the basic shape of the damage icon clearly indicated this even from a distance. If more info is needed, then they could examine that icon more closely for damage type and sub-type indicators, like color and inner shape.

Icons can display a lot, with a little planning:
The overall shape can mean something.
The color - be careful with colorblindness - consider combining with other indicators such as shape and pattern.
The actual symbol means something.
A number can be incorporated.
Relative positioning of icons might imply something.

Take a look at a recent discussion I posted:
http://www.bgdf.com/node/13501
Not saying the designs here are super great - this is more of an intermediary form - but I did manage to consolidate a deceptive amount of info and nuance into a relatively small framework that can accommodate a large amount of variation. (Though I didn't really go into all the detail in that thread, as I was mainly looking to see if people could guess at the main thrust of each ability.)