Druid Drop Hack
From Diablo Wiki
Another hack that wasn't a hack, just a bug in the game code that players found a way to exploit. This one occurred in several variations during early versions of D2X, 2001-2002. It was always something a Druid, in fur form, did when equipping items with a lot of +skills. When the item was equipped to put him over the limit, all other players on the screen would drop from the game.
The primary way this was done was by a Druid transforming into a Werewolf or Werebear with more than +13 skills from equipment. Another related issue came from casting Oak Sage when it was level 33 or higher.
The danger came when a Druid could cause other players to drop near a waypoint or the exit from town. The Druid could then return to town, go hostile, and return in time to kill the other player. Or more simply, the Druid could pull this trick when a player was surrounded by monsters, ensuring their doom from hostile demons.
Blizzard initially prevented one method by not allowing Oak Sage to gain any benefit above level 20, until a more permanent fix was implemented in a later patch.