hi guys im kinda new in this game i havent play diablo 2 for very long time since lod came out.

im a necro summoner

and i have trag set for now cheap weap cheap rings cheap boots what so ever.
my question is what to farm next.
i saw the wiki and i saw a weap that you can get on the pit but i cant kill any mobs there if i can its like forever
should i just kill cows mephisto diablo or baal. what are the rare items i can get to them that i can use to get stronger so i can move up slowly?