Mudslide

You create a landslide of mud and water, which crushes, buries, and mires those caught in its path. The mud covers the area of the spell to a depth of about 10 feet (although it might fill low-lying areas or fail to cover high points in the area, at the DM's discretion).   Creatures within the spell's effect must make a Reflex save. Those who fail take 8d6 points of damage and are buried (see Avalanches on page 90 of the Dungeon Master's Guide). Those who succeed take 3d6 points of damage and are not buried. Creatures of the Fire Subtype who are actually aflame (such as salamanders, azers, and fire elementals) instead take 8d8 or 3d8 points of damage, respectively. A creature who escapes burial ends up on top of the mudslide, mired in deep mud.   After the initial slide, the mudslide persists indefinitely, producing an area of deep bog (average depth 10 feet) until the water in it evaporates. It requires 4 squares of movement to enter 1 square of deep bog, and running or charging are impossible in the area. Underwater, the mudslide remains indefinitely, producing an area of deep muck. It costs 2 squares of movement to enter a square containing deep muck, the DC of Balance and Tumble checks increases by 5, and the DC of Move Silently checks increases by 2. Aboveground, the mud normally dries out in 2 to 3 days. A transmute mud to rock spell hardens the slide into stone, trapping any creatures still within.
 

You create a landslide of mud and water which crushes, buries, and mires all caught in its path in a 40-foot radius, 10-foot thick layer of mud.   Each creature in the area must make a Dexterity saving throw, taking 8d6 Bludgeoning damage on a failure, or half as much on a success. Fire creatures instead take 8d8 Bludgeoning damage on a failure. Each creature who fails its saving throw is buried beneath the mud, while those who succeed end up on top of the mudslide. A creature moving through the area must spend 4 feet of movement for every 1 foot it moves, and creatures cannot take the Dash action while in the mud, and lose any movement gained from such an action if they enter the mud.   The mud dries out within 3 days, at which time it can be traversed normally. Underwater, the mudslide remains indefinitely, producing an area of deep muck which costs 2 feet of movement for every 1 foot moved through it, in addition to the difficult terrain caused by swimming without a swim speed, if applicable.   A Transmute Mud to Rock spell hardens the slide into stone, trapping any creatures still within.