XCOM 2: 15 Things You Didn't Know You Could Do

12. You Can Staff The Advanced Warfare Centre With An Engineer

At some point, your soldiers are going to become gravely wounded, which, if they become shaken, will cause their will to reduce. No matter how well you strategise, someone's going to get hurt; you can prepare for such an eventuality by staffing the Advanced Warfare Centre with an engineer, thus allowing your soldiers to recover more quickly. The game does tell you about this feature, but it's an easy thing to not carry forward. Like many of these features, they're readily available in the game, but it's easy to finish several campaigns without ever having discovered them.