Cheapest priced copy (Urza's Legacy): $0.59 at Card Kingdom, near mint, their price list as of .
Damping Engine 
Artifact · Rare · Urza's Legacy · #124
A player who controls more permanents than each other player can't play lands or cast artifact, creature, or enchantment spells. That player may sacrifice a permanent of their choice for that player to ignore this effect until end of turn.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.59 to $24.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Urza's Legacy | 124 | Rare | $0.59 | $24.99 |
2 rulings from Wizards of the Coast
- 1 August 2008A player affected by this card can sacrifice a permanent any time they could cast an instant. This is a special action that doesn’t use the stack and can’t be responded to.
- 1 August 2008A player can only sacrifice a permanent to end this effect if they have more permanents than any other player, and they haven’t already sacrificed a permanent to end the effect this turn. The ability to sacrifice a creature is granted by the same effect that is being ended.