Cheapest priced copy (The List): $0.79 at Card Kingdom, near mint, their price list as of .
Impending Disaster 
Enchantment · Rare · Urza's Legacy · #82
At the beginning of your upkeep, if there are seven or more lands on the battlefield, sacrifice this enchantment and destroy all lands.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.79 to $15.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | ULG-82 | Rare | $0.79 | — |
| Urza's Legacy | 82 | Rare | $1.49 | $15.99 |
3 rulings from Wizards of the Coast
- 4 October 2004This ability does not trigger at all if there are not seven lands on the battlefield at the beginning of upkeep. It checks this number again when it is going to resolve and does not do anything if the land count is below 7.
- 4 October 2004The ability is not optional.
- 15 June 2010If this card is not on the battlefield at the times its ability resolves, then you can’t sacrifice it. However, you still destroy all lands.