Level: Druid 1, Ranger 1
Components: V, S, DF
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: Brick, stone, or earthen surface in a 40-ft.-radius spread
Saving Throw: Reflex partial; see text
Spell Resistance: No
At your command, the cobblestones of the street shudder and crack, sending your foes staggering about.
Stones, bricks, hard dirt, or any similar surface cracks and shifts in its foundations, rendering footing treacherous and potentially tripping anyone in the area. Any creature who fails its Reflex save is knocked prone. Those who remain standing can move at only half normal speed. Each round on your turn, standing creatures must make either a new Reflex save or a Balance check (their choice) to remain upright.
Because the stones continuously shift, any attempt at spellcasting requires a Concentration check (DC 15 + spell level), and any attacks made from within the area take a –2 penalty; this does not stack with the penalty for attacking while prone if the attacker failed his save.
Source: Cityscape, page 66.