Earthborn Battlements

Prevent the next X damage that would be dealt
to target creature or player, where X is the number of untapped Plains you control. If you do, tap those Plains. Each Plains tapped this way deals 1 damage to target creature or player.
"Why do humans expend such time and resources building walls? Don't they see that the earth has already done the hard work for us?"
-Nalah, goyl Cliffraiser