Cheapest priced copy (The List): $4.99 at Card Kingdom, near mint, their price list as of .
Bubbling Muck 
Sorcery · Common · The List · #UDS-54
Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
2 printings · $4.99 to $69.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | UDS-54 | Common | $4.99 | — |
| Urza's Destiny | 54 | Common | $5.49 | $69.99 |
2 rulings from Wizards of the Coast
- 4 October 2004Affects lands with type Swamp, not lands that are named “Swamp.”
- 4 October 2004Affects 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.