You command the earth beneath your feet to rise and surge forward, carrying you and your companions where you bid while rolling over enemies and obstacles in your path. The earth rises in a 15-foot-high, 15-foot‑radius swell that can carry you and up to eight other Medium creatures, propelling you in whatever direction you choose at a rate of up to 90 feet per round. You use a bonus action to direct the wave each round. Your movement is limited to the surface of the wave to maintain control. If you move off the wave, it continues on the same course you directed it, then the spell ends at the beginning of your next turn. Natural obstacles do not impede the spell's movement; trees, rocks, and other natural obstacles simply rise up and around the swell and settle back into place behind it. The wave can travel up or down natural slopes with angles as great as 60 degrees.   You can direct the wave to surge over man-made obstacles and creatures in its path. The swell washes over walls and other manufactured obstacles up to 15 feet high and 10 feet thick with no loss of movement, dealing 6d6 bludgeoning damage to an object as it passes. Resolve this damage against larger, rigid objects, such as walls, vehicles, or other similar structures; smaller or malleable objects such as unsecured ropes or cloth are simply buried by the swell's passing. Larger objects are subject to the damage, but the wave cannot move over them unless the damage is enough to destroy the object.   Creatures of Large size or smaller in the path of the wave take 6d6 bludgeoning damage and are buried. Buried creatures are considered restrained and must hold their breath or begin to suffocate. A creature in the path of the wave can make a Dexterity saving throw against your spell save DC. On a successful save, the creature takes half as much damage and avoids being buried. Each round, a buried creature can use an action to make a Strength check against your spell save DC to dig itself out.   You can cast earth wave only when standing on natural earth or stone. The spell can be cast underground, but not inside buildings unless they have no floor.