Hello everyone.
Days ago i’ve joined a server where EXP was boosted to the skies, every single trash mob was dropping legendaries and devil’s crossing was taken by Heros and Nemesis everywhere.
Was that a MOD? My game is Vanilla and i’ve never downloaded any mods or so.
Probably
/10char
It certainly wasn’t vanilla GD 
I believe for two people to play together they must both use vanilla / the same mod, so if you use no mod then maybe the host had manipulated the vanilla files, thereby overcoming that limitation.
Correct. One can edit the vanilla .arz/.arc (?) files and host a game; clients will default to the host’s files in that case, for synchronicity’s sake.
The “same mod” thing only matters insofar as playing Custom Games is concerned.
By this logic wouldn’t it be possible for expansion and non-expansion players to be able to multiplayer?