|“||Allows reaction shots to trigger on enemy attacks, not just movement.||”|
– In-Game Description, XCOM: Enemy Unknown
Covering Fire has notable synergy with Rifle Suppression, allowing reactive fire against a target who fires while suppressed, and Sentinel, allowing a Support to get two shots with Overwatch per turn as opposed to one normal.
That said, firing at enemies in cover tends to have little effect given the Aim penalty and zero critical hit chance with reactive fire and thus wastes ammo. Additionally, since the ability does not trigger until after the enemy fires, the enemy has a chance to neutralize the Support (or another soldier) with their initial shot. As such it is generally better to have a Support shoot at the enemy during the player's turn, taking advantage of any critical hit chance, especially if the Support has gained a flanking position or the enemy is otherwise exposed.
This expansion changes Covering Fire to be triggered before the enemy shoots; technically the enemy's stepping out of cover animation runs first but the gun firing animation (and damage) isn't produced until after the Cover Fire shot is resolved. Despite the animation hiccup appearing to leave the enemy exposed they will still benefit from any relevant cover bonus. Covering Fire now produces a credible chance of preventing an enemy's attack altogether. This also grants Rifle Suppression the chance to both neutralize an enemy temporarily and potentially permanently.
- Covering Fire and Sentinel are the only way for a Support soldier to make two attacks per turn (thus roughly doubling a Support's damage output, the Reaction Shots Aim penalty notwithstanding), but is reliant on getting two reaction fire chances per enemy turn, a Sentinel + Covering Fire skill build is the best way to maximize a Support's damage output. However take note that the other XCOM soldier classes all have more reliable and effective methods of making two or more attacks per turn, and arguably, a Support should be optimized toward maximizing their unique abilities instead.
- Covering Fire may not activate during Rifle Suppression.