Twinfinite: “While most of the loot will drop from slicing your way through swathes of enemies, youll also find some in chests dotted around the world. One chest in particular is proving tricky to access as you need to complete a quick puzzle before you can unlock it. So, with in mind, heres how to open Mutterlock Chests in Diablo 4. Lets go!”
Source: N4G PC How to Open Mutterlock Chests in Diablo 4