For hands-on creation, modders and enthusiasts often use item editors. A popular one for Diablo 2 is "Diablo II: Item Editor" or similar tools designed for LoD.
If you lost your CD keys, Blizzard support may help if you have proof of purchase. Otherwise, you cannot legally play the classic version today without buying Resurrected or finding a second-hand old copy (keys may be used). diablo 2 lod iso
– it’s legal, safe, easy, and the definitive way to play today. For hands-on creation, modders and enthusiasts often use