Earthflow

The world suffers the occasional mudslide or avalanche. In the Elemental Chaos, earth moves constantly in rivers of rock, dirt, or mud.

    Effect: Each area of earthflow has a direction of current (see “Underwater Terrain,”). Different sections of a single area could flow in different directions, creating a particularly turbulent earthcourse.
    Earthflow squares are difficult terrain. Each creature within an earthflow area at the start of its turn slides 3 squares in the direction of flow. If the creature is forced into an area with a different flow direction, it slides the remaining distance in the new direction. The creature must also make an Acrobatics or Athletics check to avoid sinking into the flow and becoming grabbed.
    Creatures that have earth walk ignore all earthflow effects.
    Usage: Earthflow terrain forces the characters in a certain direction or puts them at a disadvantage against creatures that have earth walk. An entire encounter area filled with earthflow can be frustrating, though, so be sure the encounter contains other terrain and rewards clever use of skills to bypass the earthflow.

Published in The Plane Below, page(s) 14.