Against some enemies, this still may not guarantee a critical hit. Attacking from stealth adds +100% critical chance.You'll be able to trigger them in terror sites and Council missions. Civilians, however, can see you perfectly.(You may still end up hurt from explosions, etc.) You won't trigger alien 'wake-up' actions when moving into their line of sight, and they won't try to attack you. Enemies behave as if you don't exist while you are invisible.

Occasionally, Ghost Mode can fail, and aliens will be alerted to that soldier's presence after moving: Ghost Mode will immediately deactivate on the rare chance that this happens.This won't trigger Overwatch attacks, but you cannot continuously stay invisible for multiple turns even if you immediately activate Ghost again on the next turn. When your turn starts your invisibility automatically ends, alerting enemies to your presence.If your soldier decloaks during the alien turn he may be attacked by any aliens that haven't yet used their actions. This could be on your turn or on the alien turn after firing from overwatch or due to Close Combat Specialist. Invisibility lasts for 1 turn or until the unit fires.It's possible to use stealth multiple times in one turn, if you have the ability to act after attacking. Activating the stealth does not cost any actions nor end the turn.Unit can become invisible up to four times per mission.

Ghost armor vs invisible shield