Rain of Stones

Area
Stones rain from the sky onto the area, causing 1d-1 crushing damage
per second to all within it. Characters and creatures under the rain of stones
take damage on their own turns; if less than an entire second is spent in the
affected area, damage is halved (round down).
The spell can only be cast outdoors. Armor protects in the usual fashion. A
shield with a DB of 2 or better can be held overhead to block the stones, but
it may take damage (p. B484). This requires two hands and a Ready
action, and succeeds automatically in protecting the character once the
shield is readied upward, but this unreadies the shield from its normal
protective functions!
Inanimate objects, such as buildings, protect with their DR.

Duration: 1 minute.
Base cost: 1 to cast (minimum 2). Same cost to maintain. For double
base cost, the Rain of Stones does 2d-2 per second!
Prerequisites: Magery 2 and Create Earth.

Item
Staff. Usable only by mages.
Energy cost to create: 500.