Raging River
Unlimited Edition — rare
Enchantment
Raging River rulings:
2008-05-01: If a creature enters the battlefield (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.
2008-05-01: If 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 others creatures that entered the battlefield after the ability resolved).