Atem's Protection is an Artifact shield of Atem. Like all artifacts, it can be obtained from Pharaohs in Pyramids, breaking a Godforged Block (Unaligned or of the god), and extremely rarely from crates and Relic Ore.
Safeguard: 20% chance to negate all damage for 10 seconds, while blocking.
The author here has a thorough "0 idea" how this actually functions. While blocking with the shield there was no sound effect or any indicator the ability triggered, and it didn't at all. I'm unsure if you have to block repeatedly to trigger it or get hit, and why you would want to negate all damage when it already has 100% damage block.