The model is not deployed as normal. Instead, at the start of any Player Turn, the owner can choose a friendly unit containing Rank-and-File models, which satisfy the following:
• The model with Hidden could normally have joined the unit.
• The model with Hidden has an identical Base Size and Height as the Rank-and-File models in the unit.
• The unit is not Shaken, is not a Summoned unit, but it can be Engaged in Combat.
After choosing an eligible unit, follow these steps:
• Remove a Rank-and-File model, with the same base size as the model with Hidden, from the front rank of the chosen unit as a casualty.
• Deploy the model with Hidden where the removed model was positioned.