Naked Singularity

Artifact, 5 (5)
Cumulative upkeep {3} (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 tapped for mana, Plains produce {R}, Islands produce {G}, Swamps produce {W}, Mountains produce {U}, and Forests produce {B} instead of any other type.¹
Illus. Mark Tedin

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: The ability generates a replacement effect.
• 10/4/2004: If a player uses a text-changing effect to make a land type be listed as producing two different colors, the player tapping the land for mana can choose to produce mana of either color. But if it produces more than one mana, all mana is of the same color.

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