Animate Rock

By employing an animate rock spell, the caster causes a stone object of up to the indicated size to move (see the animate object spell). The animated stone object must be separate (not a part of a huge boulder or the like). It follows the desire of the caster—attacking, breaking objects, blocking — while the magic lasts. It has no intelligence or volition of its own, but it follows instructions exactly as spoken. Note that only one set of instructions for one single action (the whole being simply worded and very brief — 12 words or so) can be given to the animated rock. The rock remains animated for one round per experience level of the caster. The volume of rock that can be animated is also based on the experience level of the caster—two cubic feet of stone per level—e.g., 24 cubic feet, a mass of about man-sized, at 12th level.
While the exact details of the animated rock are decided by the DM, its Armor Class is no worse than 5, and it has 1d3 hit points per cubic foot of volume. It uses the attack roll of the caster. The maximum damage it can inflict is 1d2 points per caster level (thus, a 12th-level caster's rock might inflict 12 to 24 points of damage). Movement, for a man-sized rock, is 60 feet per round. A rock generally weighs from 100 to 300 pounds per cubic foot.

Sphere: Elemental (Earth)
(Alteration)
Level: 7

Range: 40 yards
Components: V, S, M
Duration: 1 round/level
Casting Time: 1 round
Area of Effect: 2 cubic feet/level
Saving Throw: None

Material Components:
a stone and drop of the caster's blood