Invisibilty is a Resistance 2 co-op and online berserk. In co-op, it is only available for the Spec-ops class. Online, it is available for everyone. Invisibility camouflages the player so that they are practically invisible whilst the berserk is active. The player will appear slightly blurred normally but the invisibility will be temporarily disabled while the player fires or sprints.
In multiplayer it is available at level 12, and at level 4 in co-op.