Related
The chances of the Card Ability working are directly proportional to how much damage the target has taken. If the target is at half HP, the chance is about 50%, while if the target is at 1/4 HP the chances are closer to 75%. If Card succeeds, there is a small chance of getting a rare Card instead of the usual Card. Note that Monsters may also drop their Card after combat even if the Card Ability is not used.