A unit with this ability has the Ambushers special rule, with the following exceptions.
When these units enter the battle in the Remaining Moves sub-phase, they do not move onto the board as reinforcements in the normal way. Instead, when a unit that is Entombed Beneath the Sands enters the battle, place a small marker (such as a coin) anywhere on the battlefield, but not in impassable terrain or within 1" of a deployed unit.
Roll a scatter dice and an artillery dice. If you roll a Hit on the scatter dice, the marker stays in place. If you roll an arrow, move the marker the number, in inches, indicated by the artillery dice in the direction shown. If the marker is under a friendly unit, impassable terrain or a building, place it 1" away from the closest edge of the unit/terrain.
Once the final position of the marker is established, place the emerging unit in a legal formation such that it touches the marker, facing any direction. If the marker is under an enemy unit, you may place your unit into base contact with the enemy unit in their front arc; your unit will counts as charging this turn.
If you roll a misfire, or if for any reason some of the models in the unit cannot be placed, then the unit does not emerge. Instead, remove the marker and roll on the Mishap table. If a unit emerges successfully, it may act normally this turn.
Only characters that have the Entombed Beneath the Sands special rule can be deployed within such units. If you have several units Entombed Beneath the Sands, then repeat this process, one unit at a time.