The patent in question, US Patent No 6200216, was filed by Wildcat on March 6 1995 and issued on March 13 2001. It describes. among other components, "taking the traditional trading card metaphor and uniquely updating and enhancing it for application in consumer digital media." Wildcat claims the patent applies to its game 'Unit Commander' which it calls "the ultimate mercenary trading card game."
Wildcat's allegations seem to date back to a lawsuit filed last year against Wizards of the Coast and 11 other companies, including Nintendo, EA, Sony Computer Entertainment America, Sony Online Entertainment, Konami, and Zynga. The complaint pertains to the same patent infringement Wildcat is presently suing Wizards of the Coast over.
According to The Cardboard Connection, as of August 2 of this year Chaotic USA and Nintendo were dismissed without prejudice, leaving both open to being sued by Wildcat again separately. It's unclear if Wildcat's present case against Wizards of the Coast is a retooling of the previous one following a similar dismissal.