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
They're fairly useless on their own, but assemble all three and you get a whopping seven mana from just three lands
From here, which you play depends a lot on your deck
destroy an artifact, deal 4 damage to each opponent that wasn't targeted for this ability, and impulsive draw a card
We ended up adding a fourth creature type, Merfolk, and used the three-three-two-two model that I had designed for Khans of Tarkir
Each player has just four cards: three roses and one skull