Earthquake

You shake the ground, topple creatures into fissures, and collapse structures. The GM might add additional effects in certain areas. Cliffs might collapse, causing creatures to fall, or a lake might drain as fissures open up below its surface, leaving a morass of quicksand.

Shaking Ground The ground is difficult terrain, and creatures on it take a -2 circumstance penalty to attack rolls, AC, and skill checks. Spell Effect: Earthquake (Shaking Ground)

Fissures Each creature on the ground must attempt a Reflex save at the start of its turn to keep its footing and avoid falling into 40-foot-deep fissures that open beneath it. The fissures are permanent, and their sides require successful DC 15 Athletics to Climb.

Collapse Structures and ceilings might collapse. The GM rolls a flat check for each (DC 16 Flat for a sturdy structure, DC 14 Flat for an average structure and most natural formations, DC 9 Flat for a shoddy structure, all adjusted higher or lower as the GM sees fit). A collapse deals 11d6 bludgeoning damage to each creature caught in it with a basic Reflex save. A creature falls Prone unless it critically succeeds and falls into a fissure if it critically fails.