Vitrify

This spell transforms normal sand of any depth into crude glass.   The sand is instantly heated to the melting point and then slowly hardens in its new form.   Objects on or in the sand sink into the hot glass.   A creature is allowed a Reflex save to escape before the area is changed.   A creature that fails its save and that is unable to levitate, fly, or otherwise free itself sinks partway into the molten glass, reducing its speed to 5 feet and giving it a -2 penalty on attack rolls and to AC.   Creatures of the earth subtype can move only 10 feet per round slower in molten glass.   If a creature is only partially in the area (such as a Large or larger creature on the edge of the effect), it still takes full damage, but its speed is reduced only by half (instead of to 5 feet).   A creature caught in molten glass takes 10d6 points of fire damage on the first round.   The transmuted material cools over a period of 10 rounds.   Each round, the number of dice of damage the cooling glass deals is reduced by one, until it deals no damage.   The glass is solid enough to trap creatures by the sixth round.   Creatures unable to escape the glass before it hardens become trapped and must be broken out.   A creature so caught can break free by making a Strength check to break the glass or by dealing damage to the glass.   Glass has hardness 1, 1 hit point per inch of thickness, and a break DC of 12, + 1 per inch of thickness.   A creature partially caught in the glass takes a -2 penalty on attack rolls, a -4 penalty to Dexterity, and is unable to move.   When breaking glass, a creature takes 1d6 points of damage each time it makes a successful Strength check to break free.   If broken free by others, the creature takes 1d6 points of damage from broken glass.   A creature trapped beneath the surface of the glass might begin to suffocate (see page 304 of the Dungeon Master's Guide).   Arcane Material Component: A small glass marble.
 

This spell transforms a 20-foot Cube of sand into crude glass by instantly heating it to its melting point and then slowly hardening into its new form. Objects on or in the sand sink into the molten glass. Each creature standing on or in the sand as it transforms can make a Dexterity saving throw, moving to the nearest unaffected area on a success—though no more movement than their speed allows. A creature that fails its save and that is unable to levitate, fly, or otherwise free itself sinks partway into the molten glass, reducing its speed to 5 feet and giving it a -2 penalty to attack rolls and to AC. Creatures of the Earth Subtype have their speed reduced by 10 feet rather than having it reduced to 5 feet.   If a creature is only partially in the area (such as a Large or larger creature on the edge of the effect), it still takes full damage, but its speed is reduced by half rather than becoming 5 feet. A creature caught in the molten glass takes 10d6 fire damage at the start of its turn, which is reduced by 1d6 for each round the spell has been active. If a creature is partially or fully submerged in the glass after the spell has been active for at least 6 rounds, the creature is Restrained by the hardening glass.   A creature so caught can break free by making a Strength check to break the glass or by dealing damage to the glass. Glass has a hardness of 1, 1 hit point per inch of thickness, and a break DC of 12 + 1 per inch of thickness. When glass is broken within its space, a creature takes 1d6 Slashing damage from the mass amount of glass shards. A creature trapped beneath the surface of the glass may begin to suffocate.