Ok, tell me something. How do you expect to get from cata lvl 2 to andy, kill her, then from durance 2 to lvl 3 kill all the shit thats in the way of you and mephisto, kill meph, kill pindle and shenk and eldritch all in hell within 5-10 minutes?? That isnt even possible with a sorceress... Lets see here, here are some estimated times to get to and destroy the bosses you listed.

Andy- 2:00
Meph- 2:00
Pindle- 00:30
Shenk- 00:45
Eldritch- 00:20
Thresh- 00:30

Thats with a sorceress... Thats 6 minutes right there... How you expect to beat that time with a NECRO!?!?