The sand to stone spell. I heard of it but never mastered it. Give me a moment to tap into the pool.
The rustmonster begins to return to his natural Memphis form and concentrates real hard on his ring to establish a conduct to the spellpool of the order.
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free action shift shape, full round action call spell level 5
From "Sandstorm"

TRANSMUTE SAND TO STONE
Transmutation [Earth]
Level: Druid 5, sorcerer/wizard 5
Components: V, S, M/DF
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: Up to two 10-ft. cubes/level (S)
Duration: Permanent
Saving Throw: See text
Spell Resistance: No

This spell transforms a mass of sand of any depth into solid stone permanently.

Any creature in the sand is allowed a Reflex save to escape before the area is hardened to stone.
If the creature fails its save, it is entangled and can’t move. It is not considered helpless, however, and
it can break out by damaging the stone. Stone has hardness 8 and 15 hit points per inch of thickness. The creature can also make a Strength check to break free. The break DC is 20, +2 per inch of thickness of the stone.

Once the spell fills up the empty void in his mind, Mempish begins his chanting, warning everybody at forehand to move back and Intellect to widen the spell for maximum potential. When the spell begins to take shape on the eastside of the tower, its area becomes quite large. The top layer transmuted is a square of 100 feet by 100 feet, 20 ft deep. At the centre a column of 20x20 ft stretches 320 feet straight down. ((40 cubes of 20 ft each))
Weasel, purple worm shape, tunnel those rocks.
The second rustmonster comes hurrying up while exchanging his small limbs for large plates of bone. When at the centre of the stone field, he begins to dig down into the column.
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Memphis second round: Cast spell, move onto it.
Weasel: move to centre of the stonefield, free action shape change purple worm, standard action dig into stone