Roaming Pit

This spell functions as create pit, except the pit is capable of movement. As a move action, you can direct the pit to move up to 20 feet, though it must always remain on a horizontal surface large enough to accommodate its area. If the pit's movement causes it to share a space with a creature on the same horizontal surface, that creature must succeed at a Reflex saving throw or fall into the pit. Any creature that avoids falling into the pit when it reaches its new destination moves to the nearest safe space. Creatures that fall into the pit move with it if it is relocated.