Quote Originally Posted by Montatez View Post
I believe there is more enemies when you play online alone or with other people.
I don't think so. If you are in SP, you can use the players command to dictate how many "players" are in the game. So at Players 8, it tells the game there are 8 players, so monster density and hitpoints/exp/etc are set to that level. When you are playing online, you can't use the players command, but the game will still use that same principle based on how many players are actually in the game.

It's been a few years since I tried diablo 2, but I believe you can just join a game with your multiplayer character and play whatever stage/difficulty they're on.
For Diablo II there are 3 types of MP:
1. Open: where you can join games using your single player chars
2. Closed: online only chars
3. Ladder: online only chars (when/if ladder season ends, they get moved to Closed)

Open was always a problem because of the hacks and hacked items. If you want to play a legit game, you prob want to stay away from playing on Open unless you are doing private games with people who also don't want to cheat.

For example, I had once made a bow that had a 5% chance to cast summon Uber Mephisto for 30 seconds on hit, and then I could put it on my SP character and play in the Open servers.