Break the Dam!

Destroy all artifacts, enchantments, and creatures with converted mana cost X or less.
Kicker {1}{g/u}:
If the kicker was paid, permanents you control have indestructible until end of turn.
At midnight, the Ents succeeded in destroying the dam, and the river flooded the 'bowl' of Isengard, submerging everything but Orthanc and filling in all the tunnels and holes where the machinery of war had been.