If you want to play vanilla Diablo II online with friends, buy Resurrected or patch to 1.14d. The battle.net servers for 1.13c are ghost towns filled with bots.
Blizzard’s official legacy patch repository no longer hosts 1.13c (they moved to 1.14). However, the community has preserved it. diablo ii lod 1.13c download
Many players use a "legacy installer" that installs version 1.12 by default. If you want to play vanilla Diablo II
A: The official Battle.net servers force the latest patch (1.14d). You must use a private server like SlashDiablo or create a direct TCP/IP game (if your router allows port forwarding). diablo ii lod 1.13c download
It removed the lethal "Iron Maiden" curse from Oblivion Knights and improved many underpowered class skills.