Tectonic Break

You create a seismic disturbance so strong, that the earth itself cracks open and creates 1d8 long fissures five feet wide and 200 feet deep. In a 200 foot radius circle, the ground becomes difficult terrain. Each creature on the ground that is concentrating on a spell must make a Constitution saving throw. When you cast this spell and at the end of each turn you spend concentrating on it, each creature is knocked prone. This spell can have additional effects depending on the terrain, depending on the DM. 

The ground erupts  as the fissures appear, Any creature on or within 5 feet of a fissure opening up must make a Dexterity saving throw. On a failed save, the creature takes 10d6 bludgeoning damage and falls into the fissure. On a successful save, they take half as much damage and do not fall into the fissure.

Structures in area of effect that are reduced to 0 hit points while the spell is active collapse. Creatures within half the structure's height must succeed on a DC 20 Dexterity saving throw. On a failed save, they take 5d8 bludgeoning damage and are knocked prone and buried. A DC 20 Strength (athletics) check) is required as an action to escape this rubble. The DM can modify the DC up or down as they see fit depending on the nature of the rubble. On a successful save, the creature takes half as much damage and does not fall prone or become buried.