Modifications or mods as they best known are unofficial player changes to the Diablo II game data files. Some of these mods change the effects of skills, add new items, change the effect of gems, etc. These modifications can greatly expand the gameplay potential while playing them in single player and multiplayer games alike. Unfortunately certain "cheating" mods which give players an unfair advantage (the "Town Kill" mod for example) are prohibited by battle.net and will most likely result in your CD-key being banned.
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