Gravitation
When you hit a target with a gravitation weapon, you can move that target the listed distance either toward you or away from you unless it succeeds at a Reflex save (DC = 10 + 1/2 weapon’s item level + your Dexterity bonus). If this movement would cause the target to move through a wall, object, or another barrier, the target creature stops moving, but it does not fall prone or take damage. If the movement would push the target off a cliff, into a trap, or otherwise move it into an area of obvious danger, the target must succeed at a second Reflex saving throw to stop its movement or be moved into the dangerous space. Movement caused by a gravitation weapon does not trigger attacks of opportunity.
Source
Armory pg. 28