Cardians were kept inside cards until Ail and An choose to summon them. Their regular objective was to gather energy for the Makaiju. They were also incapable of speaking aside from repeating their name, or short forms of it, reflecting on their subhuman and/or bestial natures.
To summon the Cardians, Ail first shows the cards to An at random while An chooses which card she preferred the most for this mission. After An picked the selected card, she then throws the card into the air, and Ail blows the flute to awaken the Cardian inside the card.
In the original English dub, the Cardians were part of the Dark Kingdom, but unlike other agents, Cardians never disguised themselves as humans to gain an advantage, but were still capable of speech like the rest of them. All of them were females in the original anime, while in the DiC dub two cardians had their genders changed to male. The list of Cardians include:
- Hell Ant
When defeated, the Cardians simply yells "Cleansing!" before reverted back to its card form, drops onto the ground and then vanishes into the air, leaving the blank card as a result.