Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

An empire can take centuries to build but mere moments to destroy.

Double Masters

From the Vault: Annihilation

Masters Edition III

Portal Three Kingdoms

Rolling Earthquake deals X damage to each player and each creature without horsemanship. (This includes you and your creatures without horsemanship.)

Horsemanship is a keyword ability that functions similarly to flying. It appears in the Portal: Three Kingdoms set and does not appear in the Double Masters set. This means that in most cases Rolling Earthquake will simply deal X damage to each creature and each player, even creatures depicted on horseback in their illustration.