In Diablo 4, Living Steel is a rare resource and as such, it's very valuable. Players need to have it in order to unlock the Grigoire world boss fight. To summon him at World Tier 3, players will have to gather two pieces of Living Steel; on World Tier 4 they'll need five instead.

How to obtain Living Steel?

Helltide - a time-limited event that happens every two hours and fifteen minutes on World Tier Three and higher - is your best bet for acquiring Living Steel. During the Helltide event, look for Tortured Gifts of Living Steel chests which randomly appear across the open world.

When Helltide comes, the surrounding area will be bathed in blood-red colors on your map screen. This shade signals that all manner of danger (and opportunity) is nearby. Kill anything within that zone to collect Aberrant Cinders - a special currency limited specifically to this event. Once you've gathered 300 Aberrant Cinders, interact with Tortured Gifts of Living Steel chests to pick up your loot.

How to summon Grigoire using Living Steel?

Once you have some Living Steel in your inventory, you're ready for battle. Collect at least two pieces of it and an indicator known as Hall of Penitent will appear on the mini-map inside Dry Steppes. Chop down everything between yourself and Chamber of Penitence where a Light-Touched Altar awaits - use it by opening your inventory then placing the requisite number of pieces onto it.

Grigoire drops

No matter which tier of difficulty Grigoire is defeated on, everyone who emerges victorious will earn themselves a Demonbinder Mount Armor along with Penitent Greaves. Furthermore, Grigoire will shower you with class-specific rewards, so be ready to collect your spoils in Diablo 4.