Infernal Darkness

Enchantment, 2BB (4)
Cumulative upkeep-Pay {B} and 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
If a land is tapped for mana, it produces {B} instead of any other type.¹
"I thought the day had brought enough horrors for our ragged band, but the night was far worse." -Lucilde Fiksdotter, Leader of the Order of the White Shield
Illus. Phil Foglio

Gatherer Card Rulings [Nov 2009]

• 10/1/2008: This effect changes the type of mana produced, but not the amount. For example, if a land that's tapped for mana would add {W}{W} to its controller's mana pool, it adds {B}{B} to that player's mana pool instead.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard
Printings (1/6)	Ice Age (Rare)