This updates the rules given in Armour Battles for Hidden Units.
At the start of the game units may be hidden behind or in terrain. Hidden Units may be moved, but first have to be converted into a Blind. Place a Blind over the location of the Hidden Units and then move them as a Blind. Your opponent may use opportunity spotting to reveal the Blind if it enters into LOS of one or more of his units.
Spotting Hidden Units
Hidden Units are spotted in a similar manner to Blinds, except that the spotting attempt is made against a Blind-sized area of terrain (a wall, hedge, building, wood, etc). If the spotting attempt is successful, a Blind is placed on the table. If the owing player rolls more 1s than 6s against one or more successes by his opponent the units are deployed directly onto the table.
Hidden Units may use Ambush Fire. Ambush Fire may be used as opportunity fire or when a hidden unit is activated. Ambush Fire cannot be used by Hidden Units that have just been spotted.
To use Ambush Fire, place the firing unit on the table and declare that it is using Ambush Fire. The unit gains +1D to its Fire or AT dice. This may be increased further using a Wild Dice and a Staff Order.
Interdiction Fire and Hidden Units
Off-table artillery may use interdiction fire against Blind-sized areas of terrain. The player places the Impact Marker and makes an Artillery Reaction check. Roll a Deviation Dice when the battery fires for effect. Move the Impact Marker if the fire deviates. The player with the Hidden Units now determines whether any of his units are within the artillery’s burst radius. If so, he places a Blind over the units and the interdiction fire is resolved against the Blind.