The Shield of Immunity is a mystical artifact from Atlantis. It was the shield of Aticleas.
The shield was in Rico Lugosi's possession until The Peach killed him and stole it during their meeting in France.
Abbey Chase later took the shield from The Peach in Switzerland. But soon after, Hammer Shock Troops reclaimed the shield when they attempted to kill Deuce and destroyed the Danger Yacht.
Cain and Abel then delivered the shield to the Hammer Fuhrer who was transformed into Aticleas when the shield was brought together with the Helmet of Second Sight and the Sword of Sovereignty.
The three pieces of the armor was then washed away by the ocean when Hammer Island was destroyed.