Spinerock Knoll (309) [Commander 2015]

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.) This land enters tapped. {T}: Add {R}. {R}, {T}: You may play the exiled card without paying its mana cost if an opponent was dealt 7 or more damage this turn.