Bubbling Muck

Oracle Text

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional B.

Card Rulings

10/4/2004 Affects lands with type Swamp, not lands that are named “Swamp.”
10/4/2004 Affects lands tapped for rest of turn, not just swamps on the battlefield at the time it resolves. This is because it affects players and not the lands themselves.