Clow Cards are cards that possess the magical power
of the sorceror Clow Reed. Combining both Eastern and
Western magic, this magic system was compiled by Clow
himself. However, what time period, or what type of person
he was remains a puzzle.
The Spirits of Cards That Change Form Are Pranksters!?
The spirits from the cards that fly out and change form,
each can switch on their magic suggested by their name
to demonstrate their power. There are cards that come to attack,
and are kind of frightening, cards that steal and mimic voices and
appearances. Although, among the cards, they only want to pull
pranks, there are a few who are relatively harmless.
Use of the sealed cards varies from card to card,
some are more cunning, and some are not so hard to
capture. After being sealed or captured, the card's
name is written, and become able to hear the person
say the card's name. When using cards, a staff is used
to release the seal on the card. The card's spirit will
return to it's original appearance, and demonstrate
its power.
Taken from Actual Text in the Clow. Transcribed and translated above.
Click to see reasons why I have not posted any Clow Card scans