Calamitous Cave-In 
Sorcery
Calamitous Cave-In deals X damage to each creature and each planeswalker, where X is the number of Caves you control plus the number of Cave cards in your graveyard.
Legality
standardLEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL