You create a small amount of stone and rubble that clogs up the area.

At-Will   ✦     Arcane
Minor Action      Ranged 5

Effect: One square in range becomes difficult terrain until the end of the encounter. You can end this effect as a minor action.

Special: You cannot have more squares than your Intelligence modifier under this effect at one time.

Published in Dragon Magazine 383, page(s) 52.