Core · Unit · Rules

Per Squad with two or more Strong Units in a CQB, one enemy Squad of your choosing suffers -1DF for that CQB, assigned at the start of step 1 of that CQB. If both players have Strong Units involved, the player without the Initiative chooses an enemy Squad(s) to affect first.

Source: Dropzone Commander Rulebook 3.02 · 3.02 · p. 47 · unit-special-rules