Look out sir says:
Conceal says:
Use this Stratagem at the start of your opponent’s
Shooting phase. Select one ALPHA LEGION
INFANTRY unit from your army. Until the end of that
phase, enemy models can only target that unit if it is
the closest visible target.
If you use this on a unit of cultists that are within 3" of a bunch of characters and closer to the enemy than the characters but not the closest unit to the enemy, this means that the opponent cannot shoot either your cultists or your characters, correct? They would have to first kill anything closer than the cultists, then kill the cultists (down to 2 models), before they could shoot your characters?