Contamination - Mystery Booster 2 - 178

Enchantment

Mana Cost: {2}{B}

At the beginning of your upkeep, sacrifice this enchantment unless you sacrifice a creature.
If a land is tapped for mana, it produces {B} instead of any other type and amount.

Rare · Mystery Booster 2 · #178 (MB2)

Illustrated by Stephen Daniele