You deal damage to opponents when bull rushing them through difficult terrain, using the environment itself to harm your targets.
Benefit: When you successfully bull rush a creature, it takes 1d4 points of damage for every 5 feet it is pushed through naturally occurring difficult terrain. This damage is in addition to any damage the creature might normally take from moving through the difficult terrain. Creatures with the woodland stride special ability or who are otherwise unaffected by difficult terrain are immune to this extra damage.
Pathfinder Roleplaying Game Ultimate Wilderness © 2017, Paizo Inc.; Authors: Alexander Augunas, John Bennett, Robert Brookes, John Compton, Dan Dillon, Steven T. Helt, Thurston Hillman, Eric Hindley, Mikko Kallio, Jason Keeley, Isabelle Lee, Jason Nelson, Stephen Radney-MacFarland, Alex Riggs, David N. Ross, David Schwartz, Mark Seifter, Jeffery Swank, and Linda Zayas-Palmer.