Cheapest priced copy (Collectors' Edition): $29.99 at Card Kingdom, near mint, their price list as of .
Raging River 
Enchantment · Rare · Limited Edition Alpha · #168
Whenever one or more creatures you control attack, each defending player divides all creatures without flying they control into a "left" pile and a "right" pile. Then, for each attacking creature you control, choose "left" or "right." That creature can't be blocked this combat except by creatures with flying and creatures in a pile with the chosen label.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
7 printings · $29.99 to $2499.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Unlimited Edition | 169 | Rare | $229.99 | — |
| 30th Anniversary Edition | 164 | Rare | $37.99 | — |
| 30th Anniversary Edition | 461 | Rare | $199.99 | — |
| Collectors' Edition | 169 | Rare | $29.99 | — |
| Intl. Collectors' Edition | 169 | Rare | $32.99 | — |
| Limited Edition Alpha | 168 | Rare | $2499.99 | — |
| Limited Edition Beta | 169 | Rare | $449.99 | — |
2 rulings from Wizards of the Coast
- 1 May 2008If a creature is put onto the battlefield attacking after the ability resolves, it can be blocked by any creature that could normally block it (including creatures that entered after the ability resolved).
- 1 May 2008If a creature enters (or something becomes a creature) after the ability resolves, that creature will not be able to block any creature that was attacking at the time the ability resolved.