concentration, 1 minute/mana

As two actions, you create a seismic disturbance at a point on the ground that you can see within 100 meters. For the duration, an intense tremor rips through the ground in a 20-meter radius circle centered on that point and shakes creatures and structures in contact with the ground in that area.

The ground in the area becomes difficult terrain. Each creature on the ground that is concentrating must make a Will saving throw.

On a failure, the creature’s concentration is broken.

When you cast this spell and at the end of each turn you spend concentrating on it, each creature on the ground in the area must make a Reflex saving throw.

On a failure, the creature is knocked prone.

This spell can have additional effects depending on the terrain in the area, as determined by the GM.

Fissures. Fissures open throughout the spell’s area at the start of your next turn after you cast the spell. A total of 1d6 such fissures open in locations chosen by the GM. Each is 2d6 meters deep, 2 meters wide, and extends from one edge of the spell’s area to the opposite side. A creature standing on a spot where a fissure opens must succeed on a Reflex saving throw or fall in. A creature that successfully saves moves with the fissure’s edge as it opens.

A fissure that opens beneath a structure causes it to automatically collapse (see below).

Structures. The tremor deals 75 bludgeoning damage to any structure in contact with the ground in the area when you cast the spell and at the start of each of your turns until the spell ends. If a structure drops to 0 health, it collapses and potentially damages nearby creatures. A creature within half the distance of a structure’s height must make a Reflex saving throw.

On a failure, it takes 10d6 bludgeoning damage, is knocked prone, and is buried in the rubble, requiring a Difficulty 20 Brawn check as an action to escape. The GM can adjust the Difficulty higher or lower, depending on the nature of the rubble.

On a success, it takes half as much damage.