One For All is a MEC Trooper ability in XCOM: Enemy Within.

When activated, the MEC becomes a high cover element. Moving or using an arm-based weapon will return the MEC to standard posture.

– In-Game Description, XCOM: Enemy Within


  • One For All is an active, but more potent version of the Alloy S.H.I.V.'s ability Hardened Shell.
  • One For All's cover effect is cancelled if the MEC fires, moves or uses any other low-tier abilities; this includes shots fired from Overwatch. High-tier abilities such as Grenade Launcher do not cancel the effect.
  • It is possible to have a MEC do nothing during a turn. Simply move every other unit as you see fit, then hit the "end turn" button.
  • Reactive Targeting Sensors has negative synergy with One For All, as the reaction shot will return the MEC to standard posture and cancel the high cover effect.


  • Caution should be taken when choosing to use a MEC as cover as clustering two of your units together frequently triggers the enemy AI to use any available grenades.
  • One For All can be used in combination with a soldier with Mimetic Skin on maps with minimal high cover to maintain the Gene Mod's effect for as long as possible.