I almost do not exist now and I know it; God knows what lives in me in place of me.
-The Idiot, by Fydor Dostoyevsky
A short update and clarification to the rules of the Endless Whispers campaign.
A model which attempts to jump down must pass an initiative test for each 4" or fraction thereof which it descends. For example: a model which jumps down 6" must pass 2 initiative tests. If the model fails so much as one initiative test, it has failed the jump and must test for damage. Roll a D6 for each 4" or fraction thereof the model has fallen. The model takes a mortal wound for each die which comes up a 4+. If the model survives, it may not move any further.
A model which successfully leaps down and charges an enemy model within 6" of its landing point has made a "diving charge." Add one to all hit and wound rolls in melee for that model this turn.
A model may attempt to leap a section of fence by passing an initiative test. If the test is passed, the model bypasses the fence and continues moving as normal. If the model fails the test, it trips over the fence. Place it on the opposite side; the model may not move any farther this turn. A model which has 8 or more wounds destroys the section of fence regardless of whether it passes or fails the test. A behemoth-sized model ignores fences entirely as it moves (we can assume it can step over them). A behemoth may opt to destroy a section of fence as it moves over it (we can assume it kicks the fence over rather than stepping over it).
A Behemoth may not utilize gangplanks. Should a Behemoth pass through a gangplank, the entire section is destroyed. Any models on the gangplank must test for falling as described above.