Ash Cyclone

A giant ash cyclone races across the battlefield.
The Visibility (9") rule is in effect.
In addition, at the start of the battle, after both
sides have, deployed but before the first round,
place a marker in the centre of the battlefield. At
the start of each End phase, before making Bottle
tests, move the marker 3D6" in a random
direction (stopping if it comes into contact with a battlefield edge). Fighters who start or end their activation within 12" of the marker becomes
Prone and Pinne