So IMHO these are the questions that have to be clarified: Do you have to have a legal LO in your list if the mission includes this special rule? (It isn't stated, but may be required) Do you have to deploy at least one FO in a way that it is legal to choose it as LO? (It isn't stated, but may be required) What happens if you didn't deploy your only FO on the table (Hidden or AD)? - Redeployment? After reserve models? What happens if your list does not include an FO at all? - Does this make the list illegal for such a mission? While it is much harder to have an army deployed without viable Datatracker, those questions are the same for DT, I guess. And while @Mahtamori states that it would be unfair to lack a Datatracker in missions where the opponent gets Objective Points for killing the DT, you have to consider that a list without specialists would be legal for firefight, right?