The Fractured Winterglass in Diablo 4 is a unique amulet for sorcerers, helping them reduce the cooldown times of Conjuration when a Frozen Orb explodes. It also grants resistance to all elements, an increase to Conjuration Mastery, non-physical damage, and a % chance to cast Frozen Orb projectiles twice.

If you have a build around the Frozen Orb, the Fractured Winterglass can be useful because its unique effect is this: casting Frozen Orb has a [35-65]% chance to spawn a random Conjuration when it explodes. There's also a Lucky Hit affix where your Conjurations have up to a [50-90]% chance to launch a Frozen Orb at nearby enemies. If this sounds great for your build, you can get this unique amulet in D4 here.

Fractured Winterglass has a high chance of appearing as a drop from Lord Zir, so if you're focused on getting it, target this boss by delivering Exquisite Blood to the altar. To get there, head to The Darkened Way area in the Fractured Peaks region. There, you'll find the entrance to The Ancient's Seat. Once inside, find the Bloodied Altar and use Exquisite Blood to summon Lord Zir.

For the normal variant of the boss you need 9 Exquisite Blood, but for the Tormented version of Lord Zir you need 2x Stygian Stone and 27x Exquisite Blood.