To play Mayhem Cards, you need a Deck with exactly 30 Cards (and one Hero card). Mayhem Cards takes place on a battlefield that gets built up by landpieces of both players (so it’s different each game). The goal is to shrink the opponents life from 16 to zero, by destroying his creatures on the field or even attacking his hero (which represents his life on the battlefield) directly.
Mayhem Cards was developed before my Bachelor studies and got released, it wasn’t very successfull though because it still was a little bit to complexe. A next itteration would be neccessary to break it down even more to it’s essentials.