Details on how to obtain the Horadric Cube in Diablo 2 Resurrected.
In Act 2, you must obtain the Horadric Cube during the quest “The Horadric Staff”. This phase of the quest will be updated during the first quest of Act 2, [Radament’s Lair]. After you kill Radament, loot the chest near him and it’ll yield a Horadric Scroll, which you should take to Cain in town.
After that, head out of town to reach the Rocky Waste and follow the perimeter of the area until you reach the Dry Hills, wherein you can find the Halls of the Dead dungeon. Make your way to the Halls of the Dead Level 3 (be sure to grab the Waypoint of Level 2!) where you’ll find Bloodwitch the Wild (a Super Unique enemy who is always Extra Strong and Cursed) guarding a golden chest. Kill her and loot the chest to obtain the Horadric Cube.
You will need the Horadric Cube to complete key quests in Acts 2 and 3, and while it’s a bother to keep in your inventory, its 2x2 space requirement isn’t so bad when you consider its extradimensional properties, as it grants you 3x4 spaces of internal storage. To learn more about how the Horadric Cube functions, check out the following page, [How the Horadric Cube Works].