Looking back now, 5 mana is an awful lot to ask of an enchantment that doesnt do anything when it enters the battlefield, but if allowed to sit on the battlefield after a board wipe or a couple turns of play from an Aristocrats strategy (decks that derive value from sacrificing creatures), Black Market can quickly generate game-winning amounts of black mana
These error cards were given to employees at Wizards of the Coast, and the public did not learn of these cards' existence until 2006, when a former employee of WOTC spoke out about the odd mishap
First of all, it allows you to retain the previous levels type, allowing you to continue to hit for weakness
That's not to say that everything in the set was dynamite, but there were so many hits that it's often hard to remember all the strong cards in the set
But, at a bare minimum, we strongly advise using a bubble mailer